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Author Topic: No dialtone on outgoing ISDN calls with Asterisk  (Read 4738 times)

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No dialtone on outgoing ISDN calls with Asterisk
« on: Saturday, 04.03.2006 23:36 »
By default you won´t hear any dialtones when dialing an ISDN number through your Asterisk box.  Only after the call is answered or rejected by the PSTN you will be able to hear anything.

This behaviour is likely to cause irritation to users accustomed to conventional dialtones and may also cause problems on some ISDN calls where you have to dial additional numbers before the final destination is reached.

WIth the CAPI 2.0 implementation chan_capi it is easy to change this behaviour back to the old-fashioned way simply by adding /ob immediately after the CAPI dial string. For example:


will call the given number in early B3 mode with overlapped sending of numbers. If you use the PBX manager Web-GUI, simply change the Custom Dialstring of your CAPI trunk to:


Restart Asterisk, dial an ISDN number and listen to these beautiful dial tones!  :)
« Last Edit: Saturday, 04.03.2006 23:44 by admin »