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Voice over ISDN CAPI

The Common-ISDN-API (CAPI) is an Application Programming Interface standard used to access the ISDN telephony equipment connected to Basic Rate Interface (BRI) or Primary Rate Interface (PRI) lines.

By adhering to the CAPI, the PC-Telephone software uses well defined mechanism for voice and fax over ISDN, without being forced to adjust to the hardware vendor implementation.

The ISDN fax document uses Structured Fax File (SFF) format with modified Huffman compression.

Use the ISDN-IP Call Transfer list in order to transfer the incoming phone and fax calls by the called number/MSN.

In this way, your PC-Telephone softphone works like an ISDN-VoIP telephony exchange or SoftSwitch transferring incoming phone and fax calls to the corresponding computers in your IP network.

The PC-Telephone SoftPhone integration supports both VoIP and Voice over ISDN telephony and you will really find your legacy telephone and fax device obsolete.

Phone and Fax from your Computer over ISDN

Free ISDN SoftPhone and Fax software If you have ISDN telephone line (Integrated Services Digital Network), PC-Telephone software turns your computer into a digital telephone and fax machine.

You can use your computer to make and receive phone and fax calls to/from any regular telephone or fax device, either digital or analog.

Use digits only when you dial regular phone/fax numbers over ISDN.

Phone and Fax calls over ISDN

PC-Telephone enables automatically the Network-ISDN options if you have a CAPI 2.0 compliant ISDN card/modem installed.

Common-ISDN-API CAPI Software


For the list of the CAPI 2.0 compliant products visit www.capi.org

Download the free Voice over ISDN PC-Telephone Softphone to test regular Phone and Fax calls over your ISDN line.


If you do not have ISDN telephone line,
make phone and fax calls over Internet!


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