[SR-Users] Is this idea even feasible?

Raúl Alexis Betancor Santana rbetancor at serlink.es
Wed Aug 18 00:20:20 CEST 2021

On Tuesday 17 August 2021 at 21:22:37, Antony Stone wrote:

> On Tuesday 17 August 2021 at 21:55:15, Fred Posner wrote:
> > On 8/17/21 2:20 PM, Antony Stone wrote:
> > > If not, can anyone suggest something else which could sit in between a
> > > very basic SIP client and a PBX server, in order to inject these sorts
> > > of commands into the path and thereby give me these sorts of extra call
> > > capabilities?
> > 
> > This really sounds like a better use case for Asterisk, FreeSWITCH,
> > SEMS, or PJSIP.
> I know Asterisk pretty well.
> When you use it as a SIP client to register to another PBX, it is extremely 
> basic - it can place a call and it can receive a call, but it has no concept 
> of presence, it cannot send a REINVITE to put a call on hold, it cannot send a 
> REFER to transfer a call...
> I don't understand how placing this in between my simple client and the PBX 
> which is handling the call can possibly inject the commands I need.

Sorry for telling you this, but if you think that, you don't know Asterisk at all. 

You don't need to send a REINVITE to put a call on hold, just change how you handle 
the RTP of the call if you SIP endpoint doesn't support REINVITES/UPDATES.
Asterisk knows about presence, it doesn't have full implementation, but you either need it.
Also transfers doesn't force you to do them throught REFERS

> Can you point me at anything which documents how this could be possible?

The thing you need it's a B2BUA, and Asterisk, FreeSwitch, YATE, SEMS, either a simple python 
script using pjsua2 or any of the dozens SIP frameworks out there, will allow you to acomplish
your goals

If you go the Asterisk road, any of the AMI/ARI documentation will explain to you how to handle
ongoing calls.

If you prefer FreeSwitch, you will have to surf the ESL seas.

I you take the SEMS aproach, SBC + DSM/Python/xmlrpc

You could take any road you like, but not Kamailio, as it's not a B2BUA.

I suggest you, first undestand the concepts you need to manage, then you will be able to pick
up a tool for solving the problem.

Raúl Alexis Betancor Santana 
Serlink Telecom S.R.L.U.

More information about the sr-users mailing list