Dtmf detection from Alcatel digital extension

Dear Sirs,

I have an Asterisk box and an Alcatel 4400 connected via Pri/E1. My setup is: PSTN->Asterisk->Alcatel. Almost everything works fine except for Dtmf detection from Alcatel digital extensions.

Outbound calls from alcatel digital extensions works fine with a 69 prefix, i mean dialed like this: dialtone code + 69 + telephone number. For analog extensions outbound calls are dialed without 69 prefix: dialtone code + telephone number.

However, my client requires to make outbound calls from both types of extensions (analog and digital) in the same way (without 69 prefix). He told me that kind of calls is possible with asterisk, without changing Alcatel setup in any way.

I’ve found that 69 prefix changes in some way the dtmf generation, because just after that prefix is dialed, asterisk can “see” subsequent dialed dtmfs, however before that prefix asterisk can’t see anything.

Some additional data:

  • Using euroisdn (could help change this by qsig?)
  • For outboundcalls from Alcatel, using DISA on asterisk side to generate dial tone
  • Calls from Alcatel to PSTN (withouth asterisk) via E1 works fine without 69 prefix
  • I’ve tried to use Read instead DISA on asterisk with same result (still need 69 prefix)
  • hardware is a couple of TE210p Digium Cards
  • Asterisk 1.4.5

Please give me any suggestion to get working outbound calls from digital alcatel extensions without the 69 prefix.

Thanks in advance


First things first, why are you signalling using dtmf from the alcatel to the asterisk, Yes use DTMF once the call is established but all call setup should be done over the d channel.


You’re right that was my mistake, overlapdial=yes in zapata.conf solved the issue.