SIP/FXS-combo extension?


Hi everyone,

I am trying to figure out something here: we have a FXS station currently plugged-in the UCM directly and used by a few phones on the line (only 1 line anyway). Now, we want to add a SIP phone from GS and we want it to use the same extension to be able to have the same voicemail for both phones.

We looked at VM groups but it is not what we want at all. And using a dummy extension prevent us from having a MWI monitoring. The workaround using BLF can’t be used, the new phone doesn’t have BLF (DP7xx).

Anyone has found a way? I could simply use a SIP extension with multiple registration but I would need a separate HT801 to convert it again to analog. Is there a way to use the built-in FXS ports for that?


I am not aware of a way that you can mix the two technologies (SIP and analog (FXS)) to use the same extension number. Once an extension number is assigned to the FXS port, the UCM prevents its use again for SIP or FXS.


What are you talking about??

There should be a way. It’s a little bit stupid IMO.


I would use the SIP extensions VM and then set the call forwards:busy and unavailable on the FXS extension to point to *<sip_extension>


That’s a good workaround!

Although, I lose the MWI on the analog phone (which as a blinking LED if voicemail).