Understanding sip functionality, Using a sip proxy server, Verifying dialed strings – Dialogic 6.2 User Manual

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Managing Calls Using IP Telephony

November 2009

219

Understanding SIP Functionality

The following section provides information about SIP functionality

and processes. For a detailed introduction to the SIP protocol, see

Using a SIP Proxy Server

To make an outgoing connection using the IP, your application must

know the IP address of a local proxy server which is responsible for

forwarding the SIP call towards its final destination. In a typical

environment, the proxy server is the local IP to PSTN gateway. For

To receive incoming calls using the internet, you must register your

location so that proxy servers can locate you.

For more information about configuring proxy servers, see the

installation and configuration guide that came with your software

and the Bfv API Reference Manual, Volume 6, Appendix A.

Verifying Dialed Strings

If your application either does syntax verification/modification of the

dialed string or it is desirable to do number translation or lookup

without modifying the application, then the application needs to

perform number translation.

Channel numbers enable your application to differentiate between

types of call in the context of the Call Control Bfv API. SIP and other

IP protocols use a Uniform Resource Identifier (URI). The software

detects and recognizes the format of the dial string and sends the

call to the appropriate channel. In Brooktrout SDK 4.0 and beyond,

the dial strings follow the URI syntax, so tel: and fax formats are not

supported and must be reformatted by your application.

Prefixes to dial strings are provided as a means for your application

to behave intelligently by supporting channel selection in hybrid

systems. Prefixes are optional.

Using prefixes, dial strings can also be pre-qualified by your

application as in the following example: