ISDN-to-SIP Internet Telephony Gateway

This project builds a simple gateway between a regular telephone line and an IP network (Internet).

The rat audio tool and the SunShine ISDN library are already written and available. The SunShine library only deals with signaling information, not audio packets. The SIP-to-ISDN software uses the SIP C++ library being written.

1. Get CRF to re-install the ISDN line to the Sun workstation (merlot) in far right corner of lab.
2. Try out the NTE unit with a regular phone to see that it works. Documentation is in file cabinet. The NTE is in the equipment cabinet (ask Jonathan Lennox for key).
3. Install and test SunShine-based software; make sure both ISDN "B" lines work.
4. Modify rat audio software to use ISDN lines (/dev/isdn) instead of /dev/audio.
5. Create SIP user agent client/server running in workstation to receive calls from IP networks and to place calls to IP addresses. Create as SIP UAC/UAS stack, using API for parser as in sipd.

The ISDN line looks like an audio device (i.e., /dev/isdn instead of /dev/audio). Thus, existing audio tools such as rat can be modified to serve as the bridge between the network and the ISDN line.

The ISDN server is already mostly functional.

ISDN parameters

Resources

• SIP
• Description of GMD Fokus implementation of Sun ISDN library based on the SunShine library
• API documentation

record and play from/to /dev/isdn/0/te/b1

/ind/proj/irt/sar/isdn/da/sunshine/v1/q931/NEW/test/isdnCall
c 9610195 9397040 (calls 9397040)
cat sample.au > /dev/isdn/0/te/b1

• modify rat to allow opening /dev/isdn/... instead of /dev/audio
• DTMF detection in NeVoT audio reading loop; export to PMM