Presence Outbound Calls Only work from Internal

[dwcoffin]

This issue is only affecting 2 extensions, but others are working fine.
We have presence set.
Internally, if we dial 4-digit extension, Presence forwards successfully to number set in “Presence”.
Internally, if we dial 9 for an outside line and call the DID Presence forwards successfully to number set in "Presence".

However;
If we dial the DID from an external phone the call fails to forward to number set in “Presence”.

So far, the failed forwarding of the call is only happening on 2 extensions.

The numbers in "Presence" are configured like 9 555-1234 as they are in the same area code.
I've tried added modifying to 9,1 with area code and that fails also.

I've tried comparing functioning users to non-functioning users and extensions, but I'm not finding any differences.

Any assistance will be greatly appreciated.

[dwcoffin]

I just discovered that all of the cell phones that fail the presence forwarding are T-Mobile.
Another phone with Xfinity as cellular provider works fine.

\_(ツ)_/

Anyone else experience this?

[wshrader]

How does the failure happen? What does the caller hear? Are there any entries in the System Events (both without and without debug checked) that give any clues? What model and firmware is the Allworx server? If you take one of the affected extensions and use a mobile number that is not T-Mobile, does it work?
Last year there was a bug, not this, with T-Mobile that Allworx was able to mitigate by firmware. Maybe this is another one?

[dwcoffin]

Sorry for delayed response, The caller receives a message that the number dialed is no longer in service.
It does work when the caller is non-T-Mobile and the recipient is T-Mobile.
We are a bit behind on the firmware for the appliance, (Allworx 536 running 8.6.8.3).
We do have a scheduled upgrade coming next week.
I'll report back whether this resolves the issue or not.