With networks that have more than one BTS a dedicated host would almost certainly be used for OpenBSC. Integration with VoIP networks and the PSTN is possible through use of Asterisk and Linux Call Router.
The sysmoBTS could also be used in a classic GSM network and with a BSC other than OpenBSC provided that it supports the A-bis interface over IP. Or alternatively it could be used with OpenBSC connecting to a “real MSC” that supports the GSM A interface over IP.
The OsmoBTS and OpenBSC projects are still in heavy development and there are some features that may be supported by their proprietary counterparts that they do not yet support. However, it is still relatively early days; where there is demand, such features are likely to gain support in time. This technology is already finding use in commercial applications.
The sysmoBTS and projects such as OpenBSC are bringing the flexibility and economic benefits of open source to the heavily proprietary area of GSM networks, and it may just be that the seeds have been sown for the future disruption of an extremely high-value and increasingly competitive market.
Note: GSM uses licensed spectrum and operation of equipment such as the sysmoBTS without a licence from the appropriate regulatory authority is illegal in most countries.
Andrew Back (@9600) is a freelance consultant who originally trained as an electronics engineer and first used Linux in the mid-90s. He has since worked at BT's open source innovation unit, Osmosoft, founded the Open Source Hardware User Group, and more recently co-founded SolderPad – a place to collaborate on electronic design.