In recent days, we have finally merged a series of patches from Andreas Eversberg implementing what we call the MNCC [mobile network call control] API. Using this API, it is possible to glue existing PBX or other telephony applications to OpenBSC and thus add GSM extensions to your PBX.
So far, only Linux Call Router (LCR) has been extended to use this MNCC interface. Andreas reports that he has successfully established both mobile originating and mobile terminated calls to GSM extensions of his LCR PBX.
It's great to see this kind of contribution, especially in an area which I personally am not all that interested in... I still want to focus on the actual GSM side of things and implement more features as well as work on stability, the vty/telnet configuration interface, GPRS support and the recently-announced plans for implementing an actual A interface.
Right now, other projects require more time slices, but I'm still spending quite a bit of work on integrating better SMS support, with actual store-and-forward of messages in our SQL database.