Different voicemail box access code for MWI feature

[fernando.lagper]

Hello.

My name is Fernando Alba, we are the spanish representatives of Matrix Comsec , and Indian IP PBX maker. We are offering your Yealink phones as companions with our PBX since you have very good features and pricing.

While I was doing tests with Yealink T26P (station "46") I have noticed that MWI indication on "message" key works perfectly (led becomes lit when new message is available on mailbox) but you can't use "message" key
to access the voice mail box to check the message.
This behavior is very common on PBX DKP phones, where the same key that signals MWI allows the access to voice mail box when you push it.

I have found that it doesn't work as expected because T26 sends "request invite" to its own phone sip instead of sending the request invite to the voice mail box access code ("3931"). Since Yealink T26 MWI subscription doesn't allow to program a voicemail box access code ("3931"), we can't make it work.

This is what T26 sends to IP PBX when you push "message" key:

Request: INVITE sip:46@192.168.1.251:5060, with session description

This is what should be requesting.

Request: INVITE sip:3931@192.168.1.251:5060, with session description

Would you be so kind to consider to add this feature to newer firmware versions?. This potentially affects all the other Yealink phones that are sold to be used with Matrix Eternity pbx.

Currently, I got working both BLF and MWI with our PBX and only this minor thing is refraining the perfect compatibility and can be useful for other IP PBXs.

I will be glad to provide additional background and wireshark traces if needed.

Thanks in advance.