Since OsmocomBB does support SDR PHY now, the working frequency range is only limited by hardware capabilities. In other words, the "ARFCN -> frequency" calculation may be modified to add a constant frequency offset, so this will allow one to run both base stations and (OsmocomBB-based) mobile stations on any frequency (e.g. in 2.4 GHz WiFi band)!

Of course, regular GSM phones are not able to "see" any networks outside the known predefined ranges (e.g. GSM-900, DCS-1800), so they wouldn't be able to camp to a network running on some shifted frequency. But we believe that this feature can be helpful for research and development.

Update from 17.01.2019¶

The gr-gsm based transceiver, grgsm_trx, now has --freq-offset command line option, that allows to shift the baseband frequency. In order to shift the baseband frequency of the network side, OsmoTRX needs to be hacked a bit. This feature isn't merged to the master so far, please check out https://git.osmocom.org/osmo-trx/log/?h=fixeria/freq_shift.