I'm using a Sipura/Tiptel co-branded SPA-3000 with firmware release
3.1.20(GW) -- the latest, AFAIK.

I'd like a (now local, in the future distant) SIP phone to access the
SPA and be able to place calls throuh the PSTN interface; and
vice-versa, calls from the PSTN would ring the SIP phone.

The SPA-3000 instructions are quite cumbersome and the web configuration
interface is not logically organized to my mind, so I probably missed a
point: does the SPA-3000 acts as a SIP server, so a SIP phone has to
register to it ? Or is another intermediate registrar (like one of a
VOIP service provider) in the loop ?

Anyway, I could not register a SIP phone to the SPA-3000.

When a PSTN call comes in at the FX0 interface through the Line conector
(I am in 2-stage dialing, and "Off Hook While Calling VoIP" options),
the SPA-3000 answers the call and sends a dialtone, but does not
recognize DTMF keys: the dialtone simply goes on :((

Help appreciated !