I have a SPA-3000 whose PSTN interface is connected to an analog PBX
extension, and the VOIP interface is SIP registered.

I'd like VOIP incoming calls to be answered and connected to the PBX
dialtone, so I managed to put something in the dialplan like <:>SO but
it doesn't work.

I solved the problem by automatically dialling some dummy digits that do
nothing harmless to the PBX, but the goal would be NOT to dial anything.

Has anyone a clue about that ?