[dnllam]

I currently have a SPA2002 and thinking of getting a SPA3000 to go along with it so that the phones attached to my SPA2002 can access my PSTN line through the SPA3000 vice versa.

Note: the SPA2002 and SPA3000 will be connected to two seperate external IP addresses.

Can anyone shed some light as to whether it would be possible to do an "unattended call transfer" when I receive a PSTN call on Line 1 of my SPA3000 to my phones attached to the SPA2002 (FWD/Sipphone)? (What I am talking about is different from "call forwarding" where the incoming call gets forwarded without me answering the phone first).

In other words, someone would call me on my PSTN line, and I would answer. The caller would then ask if they could speak to someone in the other room. I would then press flash, and dial the Sipphone number associated with the phone connected to the SPA2002 (in the other room) and hangup. The phone at the SPA2002 (in the room) would then ring (the call would be transferred).

Currently, on my SPA2002, I can transfer calls using the above method between my Sipphone and FWD accounts. For example, someone would call me at my Sipphone number, and I would "flash", dial my FWD number and hangup. The calling party would then hear ringback and would be transferred to my FWD number.

[mberlant]

An SPA has no decisionmaking capability inherent in it. This means that it must be slaved to a SIP switch of some sort to accomplish what you want. When you initiate a Call Forward or Transfer operation what is really happening is that your SPA is sending a request to the SIP switch (your service provider, Asterisk PABX, etc.) to perform the desired function. It is not happening directly inside your SPA.

By the way, you do not need separate external IP addresses to accomplish any of this, since your two SPAs will be clients of some server switch.