Hi Alina,
I'm very busy at the moment preparing the sysmocom office move, so let me just add very few notes.
On Tue, Apr 02, 2024 at 05:25:55PM +0300, Alina Androne wrote:
How can I utilize the iCE40 E1 USB adapter to transition from E1 to IP in a GSM network, connecting a physical Siemens BSC (which has a BTS connected) to OsmoMSC?
You will need something that can translate circuit-switched SS7 (MTP2/MTP3/SCCP/BSSAP) to 3GPP AoIP (SCTP/M3UA/SCCP/BSSAP). This can be done for example with a real/physical Cisco ITP. But then you wouldn't need any icE1usb.
Alternatively, if you go for icE1usb, I would recommend trying to use DAHDI as driver and yate as softswitch that can do the CS7-MTP2-MTP3 to M3UA translation.
Note that all of the above is just for the signaling, and not for the voice calls.
We do not currently support interfacing any circuit-switched BSCs for voice. While this is exciting from a retrocomputing / retronetworking point of view, it has some rather different challenges than what we've done so far: Support E1/TDM only on the Abis interface and then do AoIP on the A side between OsmoBSC and OsmoMSC.
There are significant differences between TDM based A and AoIP, well into the signaling - and also regarding voice codecs. In AoIP there's no BSC-colocated transcoder... while in classic TDM based A interface there normally is, and you have PCMA/PCMU.