FreeCalypso > hg > themwi-system-sw

annotate README @ 193:1f9a6cede2c5

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
sip-manual-out: split user_cmd.c from disc_cmd.c
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 17 Mar 2023 14:31:54 -0800
parents b259e2722485
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 This Hg repository contains a work-in-progress named Themyscira Wireless system
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 software. Themyscira Wireless (ThemWi) is an experimental GSM network operated
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 by Mother Mychaela of FreeCalypso at a semi-urban/semi-rural location in
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 Southern California, USA; this GSM network is operated with Osmocom CNI software
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5 components, all running on a single Slackware Linux server. ThemWi system sw
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
6 is a suite of daemon processes and command line tools that run on the same
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
7 machine as all those Osmocom sw components and provide some additional
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 functionality that is not provided "out of the box" by Osmocom, most important
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 of which is outside connectivity to USA PSTN.
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 We are currently experimenting with using bulkvs.com as our USA PSTN
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 connectivity provider. Like most low-cost PSTN connectivity providers, they
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13 provide the interface to PSTN in the form of a SIP trunk - while I would
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 absolutely love to get a traditional TDM trunk instead, with SS7 signaling,
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15 such a toy would be far beyond my budget, hence I have to settle for SIP.
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 Our current status is:
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18 * We have already obtained a block of USA phone numbers (NANP, chosen numbers
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
19 from an exchange area local to us) from BulkVS.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
20
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
21 * These BulkVS-sourced real NANP numbers have been entered as MSISDNs into
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
22 OsmoHLR records for our test SIMs operating on ThemWi GSM.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
23
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
24 * We can successfully dial calls from one ThemWi GSM phone to another, with our
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
25 themwi-mncc switch understanding all dialing formats that are considered
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
26 standard for cellular phone networks in USA (full international, or 11 digits
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
27 starting with '1' but no '+', or 10 digits only), as well as our own non-
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
28 standard shorthand dialing method with only 4 digits.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
29
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
30 * Whenever someone dials one of our NANP numbers from the outside world, BulkVS
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
31 servers send UDP SIP INVITE packets to our server. Our inbound call gateway
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
32 process is themwi-sip-in; this daemon process listens on UDP port 5060,
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
33 accepts SIP calls from BulkVS (ultimately coming from global worldwide PSTN)
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
34 and turns them into GSM MT calls in MNCC format, going through themwi-mncc
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
35 and ultimately to OsmoMSC.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
36
178
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
37 * Our outbound call gateway is themwi-sip-out, serving as a counterpart to
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
38 themwi-sip-in. All GSM MO calls are initially handled by themwi-mncc, which
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
39 decides (based on the dialed number) whether to switch the call locally
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
40 (calling another ThemWi GSM phone) or to pass it to themwi-sip-out. The
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
41 latter process turns outbound calls into SIP and sends them to BulkVS, and we
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
42 are successfully able to call any PSTN destination anywhere in the +1 country
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
43 code. (themwi-sip-out has provisions for international routes too, but we
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
44 haven't set up any yet.)
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
45
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
46 * These inbound and outbound calls per the previous two bullet points also
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
47 include fully working voice path, with our themwi-mgw transcoding the two RTP
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
48 streams (one in each direction) between the original GSM 06.10 codec or
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
49 GSM 06.60 EFR codec on the GSM side and G.711 PCMU or PCMA on the PSTN-via-SIP
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
50 side. This voice call gateway includes working DTMF support: START DTMF and
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
51 STOP DTMF commands from GSM phones pass through OsmoMSC, themwi-mncc and
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
52 themwi-sip-{in,out} to themwi-mgw, and the latter process injects in-band DTMF
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
53 tones into the G.711 RTP stream that is otherwise generated by transcoding
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
54 from GSM voice codecs.
129
b7cd66acb123 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 88
diff changeset
55
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
56 The following functionality remains to be implemented:
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
57
178
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
58 * The only GSM codecs currently supported are the original FR (GSM 06.10) and
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
59 EFR (GSM 06.60). At some point it would be nice to add support for AMR and
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
60 maybe even HR1, purely for demonstration of its poor voice quality.
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
61
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
62 * The Presiding High Priestess of Themyscira Wireless has a desire to implement
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
63 in-band GSM 08.62 TFO inside our G.711 RTP interface to outside PSTN. Right
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
64 now if a call is connected between a ThemWi GSM phone on one end and another
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
65 GSM phone on some other network anywhere else in the world, an undesirable
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
66 tandem transcoding takes place: two lossy GSM speech codecs run in tandem,
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
67 one on the ThemWi GSM leg of the call and another on the distant GSM network's
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
68 leg, with a G.711 64 kbps connection in between. If we implement GSM 08.62
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
69 TFO inside our G.711 RTP interface which we present to the outside world, we
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
70 shall achieve TFO calls at least between ThemWi and any other community GSM
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
71 networks using our software, and maybe even between ThemWi and some legacy
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
72 commercial GSM networks, if any still remain in parts of the world that are
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
73 accessible to us.
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
74
178
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
75 * No work whatsoever has been done on SMS as of yet - all of our ThemWi work so
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
76 far has been in support of voice call functionality only. Adding SMS support
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
77 will require 3 major areas of work:
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
78
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
79 1) We will need to climb the learning curve and assess the current state of SMS
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
80 support in Osmocom CNI software.
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
81
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
82 2) We'll have to find a USA PSTN connectivity provider who supports P2P SMS: if
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
83 we are operating a GSM network and providing mobile phone service to human
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
84 end users, any SMS usage in such scenario MUST be classified as P2P rather
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
85 than A2P. However, gaining access to P2P SMS in USA telecom environment is
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
86 currently very difficult (every major provider forcibly imposes A2P
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
87 misclassification with no option of P2P correct classification), in stark
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
88 contrast to very easy and cheap access to voice PSTN with NANP phone numbers.
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
89
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
90 3) When and if we find that necessary USA PSTN connectivity provider with P2P
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
91 SMS provision, we will need to implement whatever software will be needed to
b259e2722485 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 129
diff changeset
92 interconnect it with an OsmoCNI GSM network, likely a custom SMSC.
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
93
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
94 Differences from osmo-sip-connector
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
95 -----------------------------------
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
96
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
97 In the Osmocom community, the "standard" (or generally accepted) way to connect
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
98 a GSM voice network to the outside world is via osmo-sip-connector, an Osmocom
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
99 process that connects to OsmoMSC's MNCC socket on one end and talks SIP on the
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
100 other end. Our combination of themwi-mncc, themwi-sip-in and themwi-sip-out
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
101 effectively takes the place of osmo-sip-connector. Here are the principal ways
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
102 in which our solution differs from osmo-sip-connector:
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
103
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
104 * o-s-c is designed to connect to a local instance of a SIP PBX such as Asterisk
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
105 or FreeSWITCH, as opposed to interfacing directly to an outside SIP trunk
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
106 from/to a PSTN-via-SIP connectivity provider. themwi-system-sw is different
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
107 in this regard: we do NOT use Asterisk or FreeSWITCH or any other similar
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
108 software of "spaceship" complexity, instead our themwi-sip-in and
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
109 themwi-sip-out processes interface directly to our PSTN-via-SIP connectivity
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
110 provider.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
111
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
112 * o-s-c has no internal call switching function for calls from one local GSM
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
113 phone to another, instead such switching is punted to the required Asterisk
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
114 or FreeSWITCH etc. With o-s-c, the calling phone's MO call is converted to
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
115 SIP, then Asterisk or other PBX hairpins it back to o-s-c, and then o-s-c
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
116 handles the destination call leg as a separate conversion from SIP back to
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
117 GSM MNCC. In our solution such local calls are switched internally inside
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
118 themwi-mncc, staying native within GSM MNCC land and never turning into SIP.
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
119
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
120 * o-s-c is based on Sofia-SIP, which in turn uses glib - a very unpleasant
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
121 dependency in this Mother's opinion. In contrast, our implementation of SIP
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
122 is 100% from scratch, written in plain C in the traditional Falconian coding
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
123 style.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
124
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
125 The need for RTP voice transcoding
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
126 ----------------------------------
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
127
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
128 In the context of GSM voice codecs, the term "transcoding" is used in two
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
129 significantly different meanings:
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
130
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
131 * Transcoding from one lossy GSM codec to another effectively constitutes two
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
132 lossy speech codecs running in tandem, and is a highly undesirable condition.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
133
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
134 * Running a single GSM codec (not two in tandem), decoding from GSM to G.711 in
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
135 one direction and encoding from G.711 in the other direction, is a standard
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
136 required function for traditional voice gateways between GSM and PSTN.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
137
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
138 In themwi-system-sw, we need to do transcoding in the second sense above.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
139 BulkVS SIP call interface to PSTN does not support any of GSM codecs, they only
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
140 support G.711 and G.729, and the same situation is expected to hold with other
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
141 PSTN-via-SIP connectivity providers. We certainly don't want to use G.729 - we
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
142 don't want to run two lossy speech codecs in tandem, first GSM and then G.729 -
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
143 hence the only codecs we speak on the PSTN-via-SIP side of our gateway are PCMU
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
144 and PCMA. Therefore, we need to perform RTP transcoding in our themwi-mgw,
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
145 very similar to a traditional GSM TRAU.
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
146
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
147 On the GSM side, the two codecs of most interest to us at the present time are
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
148 the original FR and EFR - hence they will be the first to be supported. Note
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
149 the big difference from other Osmocom-using GSM community networks which
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
150 typically prefer or even strictly require AMR instead! Our reasons for focusing
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
151 on FR and EFR instead of AMR are:
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
152
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
153 * Our OsmoBSC time slot configuration is full rate channels only, no half rate
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
154 channels. HR channels are needed only for greater capacity of simultaneous
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
155 calls, but with the total number of people *on the planet* who actively want
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
156 GSM/2G as opposed to LTE or 5G being no more than maybe 10, the thought of
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
157 exceeding the limit of 6 simultaneous call legs per cell (meaning 6 separate
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
158 GSM phone handsets talking *at the same time*) is preposterous.
29
dffcae9bc8a3 add README
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
159
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
160 * Without any HR channels in OsmoBSC config, AMR means AMR-FR specifically, not
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
161 AMR-HR. The highest level of AMR-FR is identical with EFR - thus if we
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
162 support EFR, do we really need AMR?
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
163
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
164 * The whole point of Themyscira Wireless is to provide service to *vintage*
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
165 mobile phones. Our current collection of vintage phones includes models that
129
b7cd66acb123 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 88
diff changeset
166 only support FR1 and EFR (Ericsson I888, Nokia 5190 and 6190), as well as
b7cd66acb123 README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 88
diff changeset
167 Calypso C05 which supports FR1, EFR and HR1, but not AMR.
88
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
168
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
169 * EFR is desirable because it gives better voice quality than FR1, but we must
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
170 support FR1 too, so we can serve the very oldest of phones which support only
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
171 FR1 and nothing else.
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
172
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
173 Voice codec restriction (forcing GSM phones to use EFR instead of AMR, or
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
174 forcing all the way down to FR1) is done in OsmoBSC config, with codec-list
97317ede320a README: update for current status
Mychaela Falconia <falcon@freecalypso.org>
parents: 29
diff changeset
175 setting under 'msc 0'.