[Freeswitch-users] Modems

[Ken Gillett]

Well that's the alternative, but I confess to being unclear on one aspect of such devices.

In a simple scenario of several SIP devices registered to a SIP server plus a PSTN analog line, it is relatively simple to see how PSTN to VOIP bridging can be implemented with a gateway device that includes an FXS, FXO and ethernet port. An incoming call on the PSTN causes the gateway to initiate a call via the SIP server to SIP client devices registered on that ID and then putting the 2 ends of the call together so the PSTN call is 'bridged' onto VOIP and being handled by a SIP client device, i.e. a softphone or SIP telephone.

But what about the reverse? My requirement is not only for the above basic ATA, but to be able to bridge VOIP to PSTN. IOW so that a SIP client can make an outgoing call onto the PSTN. Both the gateway and the SIP client are registered to a SIP server (same one in fact), how does the SIP client place a call onto the PSTN? The gateway is not a SIP server, what is the process by which a SIP client can tell such a gateway to place a call on the PSTN to the number that is somehow provided to the gateway by the SIP client? 

I am actually trying this out with a Zoom 5801 which with an FXO and FXS port and the ability to bridge in both directions can apparently do what I require, but I cannot get my head around what I am even trying to get it to do. And this is before I've even thought about bringing FreeSwitch into the equation.

I'd be grateful for any advice about this. Thanks.


On 8 Aug 2010, at 20:49, Tony Graziano wrote:

> You can always use a standalone sip gateway (patton, audiocodes, etc.).
> 
> On 8/8/10, Ken Gillett <ken at ukgb.net> wrote:
>> I asked this before, but never got any response, so hope someone can help me
>> this time.
>> 
>> Is it possible to use a (USB) modem as a 'trunk' to and from the PSTN, i.e.
>> be able to accept incoming PSTN calls and also make PSTN calls?
>> 
>> I plan on installing FreeSwitch on a Mac and it would be really handy to be
>> able to use Apple's USB modem in this way as otherwise there's no way to add
>> such PSTN functionality on the Mac Mini.  Although my requirement is Mac
>> based, I guess this question applies to any FreeSwitch installation.



Ken G i l l e t t

_/_/_/_/_/_/_/_/