Nokia and Intel have announced oFono, an open source telephony solution based on Linux. oFono is licensed under GPLv2, and it includes a high-level D-Bus API for use by telephony applications of any license.

oFono also includes a low-level plug-in API for integrating with Open Source as well as third party telephony stacks, cellular modems and storage back-ends. The plug-in API functionality is modeled on public standards, in particular 3GPP TS 27.007 “AT command set for User Equipment (UE).”

oFono.org invites developers to maintain the current project by joining their community. If you are a developer then I suggest you take a peek at their site and maybe help out.