Use Asterisk as voicemail of PABX


I have an existing system a fairly old Matra PABX that does not have voicemail.
I want to use Asterisk to equip it.
I will use analog ports for the links between the 2 devices.

I asked myself the question about the notification of the phone of the user.
My PABX works with DTMF Q23. It will be necessary that Asterisk can analyze what the PABX sends, and Asterisk can also send DTMF analyzed by the PABX to notifyor denote the phone for example.

Is this possible?


MF4 is much better known than Q dot 23 as a name for in band DTMF.

Asterisk can send and decode in band DTMF.

The issues you are likely to have are with answer and disconnect supervision, rather than with tone signalling.

My PABX is a Matra 6550. It doesnt support MF4

For a voicemail it supports V24 ou Q23…only
I don’t think asterisk support V24.

Only Q23 can be a issue for ma project.
But if Asterisk dont support decode Q23 AND send DTMF code for PABX, the features will be limited

what do you think?

In what way does Q.23 (not Q23) differ from MF4? As far as I can tell, given the poor scan of the image, from!!PDF-E&lang=e&type=items , it uses the exact same frequencies, and the Wikipedia article for DTMF quotes the Q.23 specification as one of its sources.

Effectively I had the impression that it was a different operation, error on my part. However, asterisk can send a DTMF on the analog channel when a message on the voice mailbox?

Does your PBX speak SMDI? I’ve never used it but Asterisk has support to send voicemail notifications over serial.

Fair warning, res_smdi isn’t something we’ve touched in 10 years - 2008. YMMV.

I’ve not used voicemail, so I don’t know if there is a simple way of testing the state of a mailbox, from the dialplan.


sorry I had to work on something else. But now I come back to the subject.

Thanks for your ansvers

My PABX manages the SMDI according to the docs
Do you have any other information about managing this feature on asterisk?

thank you

And also on the V24 port of the Asterisk waiting for X28