[Asterisk-Dev] Re: MP1327 trunked radio channel...

[Roman Sidler]

>Axel Schlueter wrote:
>> Hi,
>>
>> I'd like to implement a channel to connect asterisk to a
>> MPT1327 analogue trunked radio. I hadn't implemented something
>> for asterisk before, could you give me some pointers for
>> documentation ? I studied the implemantion of chan_oss.c,
>> but I'm not quite sure if it would be better to create a
>> new channel or instead write a zaptel device driver. Any
>> hints ? And one last question: I will need a "Push to talk"
>> functionality. Is there any infrastructure in asterisk which
>> supports PTT-like operation for radios ? I don't want to use a
>> VOX PTT. I've seen the "key/unkey radio" control frames in
>> the IAX2 protocol, could these be used by an IAX client to
>> trigger PTT ?
>>
>Hi,

>i am also interestet in "push to talk" functionality.

>Is there anything new about it?

We're working on similar applications.
PTT for radio, announcements and other simplex calls.
We use our proprietary SIP-UA as Terminals. For Push signal we send a SIP
ReInvite
with "a=sendrecv" and  "a=recvonly" for release.
Asterisk internally the "key/unkey radio" frame is used.
This frame must cross the bridge and/or conference.
For Channel Setup I use a channel variable RADIO=1, which may be token by
the destination channel.

It works well for SIP, later IAX, unfortunately limited to our
SIP-terminals.
Perhaps this gives some idea.

Roman