[Asterisk-Users] Integrating Asterisk with an existing PBX

[Richard Scobie]

I am hoping to implement an asterisk system between two offices as below

|-------|
| PBX   |-----(XXX)--[asterisk]---[VPN]----[asterisk]--(FXO)--phone
|-------|                                         |
                                                   |-(FXS)--PSTN

I am unsure which interface I need to connect the existing analog 
(Panasonic) PBX to asterisk, assuming  I will be connecting on the 
office side of the PBX (making the asterisk an extension on the PBX).

I am assuming it will be an FXO and envisage using Zaptel interfaces. 
Replacing the PBX with asterisk is not an option at this stage.

As I am in New Zealand, which uses different ring tones/cadences to the 
US, are there any issues there?

Any comments, caveats on this setup gratefully received.

Regards,

Richard Scobie