Connect Asterisk to Telrad PBX


I have a Telrad system in the UK and have a VOIP link to my office in Spain - e.g. we have a VOIP phone in Spain that connects to the PBX in the UK to dial out / receive calls. The data is carried over a secure VPN.

Does anyone know if it is possible to connect Asterisk (or any other variation) to my Telrad system ?

I would like to run more than one phone in Spain and thought it might be a way to go…

Failing that, are there any open source soft phones that would connect to the Telrad exchange? I can get the exchange in the UK reprogrammed for extra lines / extensions if need be.

Any suggestions gratefully received.

B. Rgds