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Controlling ISDN Messaging in TCL: LEG ALERT & LEG SETUPACK

PROBLEM: Certain carriers disconnect calls if they do not receive an ISDN:Alerting message back within a given amount of time.

ATTEMPTED SOLUTION 1: Get the carrier to increase their T310 timers (set at 20 seconds on my side, but only 10 seconds on their side). PROBLEM: They can't/don't know how/refuse.

ATTEMPTED SOLUTION 2: Using my TCL, send out an immediate ISDN:alerting message (but not in-band). Ok, great:

leg alert leg_incoming

This disconnects call because I have not yet sent a "leg setupack" yet as specified at the top of page 3-19 in the TCL 2.0 guide. This was expected.

Now for the really weird part:

<b>leg setupack leg_incoming

leg alert leg_incoming</b>

According to the NOTE in TCL2.0 Guide page 3-31 by issuing the command "setupack", "The ISDN state machine actually connects the incoming call on a setup acknowledgement"

Lovely, so what is the point of "leg alert" if it can only be issued after a "leg setupack" which connects the call ??

And, as we all know connected call legs cost money! Even if they are incoming legs (think toll-free).

Any help or suggestions would be greatly appreciated.

Community Member

Re: Controlling ISDN Messaging in TCL: LEG ALERT & LEG SETUPACK

First, this forum is for XML developers, not tcl. Please constrain your posts to XML development.

The problem is the inter-carrier signaling, and you will face problems getting carriers to change the signaling/timers. Especially since what they are doing is not technically wrong. We have run into this with the CallManager, and by setting the CTI req timer to 35 we were able to work around this. Contact the Developer Support personnel who handle tcl related issues for more help.

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