Asterisk and Legacy PBX

Hi all,

I have been talking with a friend who wants to add a “call back” link to their website and after having been playing with asterisk for the last 2 yrs on and off said that it would be able to do what he want. After telling him all about it he is keen to put an * box in to play with but he doesn’t want to bin their current PBX as yet.

What I was wondering is can * be introduced to this environment and work as follows:

  • “call back” link click on site and customer enters phone number
    • connects to a salesman on the legacy PBX
  • Once connected * then dials out to the customer either through an inbuilt ISDN2 card in the * box or by creating the call out of the Legacy PBX and connecting the two calls.

I know that integration is possible between * and legacy PBX systems but it’s whether it is possible the way that I am looking at it.

Also if this is possible then what pieces of hardware etc would be required to achieve it. I understand there will need to be analog extensions available in the PBX to interface but what additional parts will be needed.

Hopefully this will all make sense, many thanks in advance.

This should be easily done. you just need to connect to the Legacy PBX either through a SIP bridge or through analog lines then Dial one of those lines to connect to a salesman and then dial the callback number and connect the 2 lines.



Hi Jag5x5,

Thanks for the quick response, this is about what I though would be the setup. I presume that this would be routing the outbound call through * and bridging with analog extentions off the old PBX.
What, if any, analog adapters have you had best experiences with? to date I have tried a clone X100P (bad echo and volume problems), SPA-3000 (still not quite there but better) and a TDM-400 with 2 x FXO (not really had chance to eval this though). Just be nice to get another opinion on the analog gear.

Many thanks,


TDM400 with FX0 modules has been good to me!

Hi Rob

This is realy two things, Both very simple in theory and can be in practice.

Callback is done with simple PHP script on the customer site and the server end on the * connecting to the manager interface. (I Have this working with email notification and logfile), Sone to have location support added(IE limiting callers to only specified countries)

Intergration to a legacy PBX can be complicated, What system is it and what Trunks/extensions does it have, TBH you need to use either ISDN2 or E1/T1 as using fxo/fxs can lock up and wont pass cli etc. I have connected via ISDN2 and PRI to Mitel systems with no probs.



Which Mitels have you interfaced with? I’m looking at trying to interface an Asterisk box with a SX2000 Light. Unfortunately I can’t add anymore T1’s to the Mitel. I have several 8 port FXO SIP gateways that I am thinking of using or would you recomment a T1 card in the Asterisk box and a channel bank? Just looking for a little direction as I am new to Asterisk and telephony.