Managing Calls Using IP Telephony

SIP/T38://+01-781-555-1212

ISDN://+01-781-449-9009

When the current FAX.C sample program is compiled, it takes command line parameters to define the number dialed. With no changes to the source code, you can replace the number with a URI to allow it to take advantage of T.38. The sample program is effectively IP-enabled purely by virtue of the dial string it uses.

In a SIP environment, the following command:

fax –u 0 –s xxxxx@brooktrout.com foo.pkt

initiates the following sequence of events:

1.Call control processes the URI dial string.

2.Sends it to the SIP protocol stack.

3.The SIP protocol stack sends it to the SIP redirect server.

4.The SIP redirect server tells the SIP stack where calls to brooktrout.com should go.

Note: Redirect and proxy servers are optional. You can send an INVITE directly to a user client.

5.SIP stack places the call there.

6.Remote SIP proxy optionally redirects call to where it ought to go.

If the phone number string contains a prefix or characters followed by a colon(:) and the prefix is not SIP, the software sends a return status indicating that the number the application dialed was invalid.

November 2009

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