[Asterisk-Users] 56K Dialup and VOIP over same PRIs

[George Pajari]

Ian White wrote:
> Anybody have suggestions on having a 56K dialpool and VOIP connections 
> with an Asterisk box over the same set of PRIs? We've done the PM3 
> with PRIs for just dialup, but are looking for a way to integrate our 
> Asterisk box and move our voice calls onto the same PRIs.

No problem except for the detail of how to segregate the calls. There 
are two obvious approaches: put switching gear in front of your PM3 and 
Asterisk box to send calls to the correct place or have Asterisk do the 
switching.

The mechanism we used for a similar set-up was to use a WCT411P 
Quad-Card set up in the following manner:

Port 1: echo can enabled, slave clock, connected to PRI 1
Port 2: echo can enabled, slave clock, connected to PRI 2
Port 3: echo can disabled, master clock, cross connect to modem equipment
Port 4: echo can disabled, master clock, cross connect to modem equipment

Our dialplan then looks at calls coming in on the PRIs and if it was a 
voice DID that was dialled, handles the call directly. If it was a modem 
DID that was dialled, Asterisk passes the call to the modem equipment. 
The nice thing about the above approach (as we are told by Digium) is 
that the TE411P card does timeslot switching on the card so that the 
actual traffic in on the PRI and out to the modem equipment has no 
latency and, much more importantly, no opportunity for clock slips which 
can wreak havoc with modem calls. And the WCT411P is a lot less 
expensive that a six-port Adtran to do the switching in front of the 
Asterisk and modem equipment.

Contact me directly (I'm just across the Strait from you) if you need 
more assistance with the above.

g.

-- 
George Pajari, netVOICE communications    604 484 VOIP (484 8647 x102)
Open Source VoIP/Telephony Specialists  1 877 NET VOIP (638 8647 x102)
                  www.netvoice.ca  www.ip-centrex.ca
      www.digium.ca www.grandstream.ca www.sipura.ca www.snom.ca