FreeCalypso still alive in 2022

[Das Signal]

Hi Mychaela,

Indeed I was thinking of the 001-01 test PLMN, however you are right
that a MCC/MNC starting with 0 could be problematic. Instead, you could
use the 999-99 (or 999-999) PLMN :-) In addition, looking at
https://en.wikipedia.org/wiki/Mobile_Network_Code I see several 901-xx
where xx is unsassigned and could be reused. My main concern was that
if you were to use eg. T-Mobile's 310-160, then other GSM phones
with a T-Mobile issued SIM card would be at risk of inadvertently being
connected, for example someone driving by. The risk would be much lower
with a test PLMN; since it is not their HPLMN, passers-by's phones
would have no reason to attach. Also, I would recommend looking at
the available spectrum with osmocom_fft plus an SDR such as:
https://www.nooelec.com/store/nesdr-smart-xtr-sdr.html; and mapping
the existing base stations with gr-gsm. In this way you can pick an
ARFCN that has the lowest chance of stepping on the toes of an
nearby base station :-)

--DS