The following table is believed to be the complete set of all SDSL data rates
ever used by the superset of all existing flavors of SDSL/2B1Q:

Data rate    Origin
144 kbps     RS8973 pref
160 kbps     Bt8960, CM
192 kbps     Nokia Nx64
208 kbps     CM (half of 416 kbps)
272 kbps     RS8973 pref
288 kbps[*]  Bt8960
320 kbps     CM (160 * 2)
384 kbps     Nokia Nx64
392 kbps[*]  CM prototype (half of 784 kbps)
400 kbps     RS8973 pref
416 kbps     Bt8960, CM
528 kbps     RS8973 pref
768 kbps     Nokia Nx64
784 kbps     HDSL, CM, RS8973 pref
1040 kbps    CM
1152 kbps    Nokia Nx64
1168 kbps    HDSL, RS8973 pref
1536 kbps    Nokia Nx64
1552 kbps    RS8973 pref
1568 kbps    CM (784 * 2)
2320 kbps    HDSL, RS8973 pref

[*] These two data rates seem to have been used only in prototypes
    and not in any deployed SDSL product.

The CR201s board has a Bt8970 bitpump, hence we can't set data rates as easily
as on an RS8973, but we have managed to implement all of the above rates with
the exception of 2320 kbps by programming the ICD2053 clock synthesiser.
The exact nominal clock frequency is produced for each rate.
See icd2053-prog for the full details.

Note that the Bt8970 datasheet specifies operation at data rates from 160 to
1552 kbps, so if you want to run at 144 kbps, you'll be technically operating
out of spec.  But then CM did the same (in the other direction) by operating
at 1568 kbps, so figure...  Note that SDSL at 144 kbps is NOT IDSL, and the
resulting 72 kbaud symbol rate is actually *less* than the 80 kbaud of ISDN.

There is no way Bt8970 will work at 2320 kbps though, that is well above the
maximum it's designed for.  Not to mention that the ICD2053 on CR201s cannot
produce the corresponding frequency either from its 4.096 MHz reference.
