Incoming calls anonymous - Ressource account assigned to call group

[meisterheister]

Hello community,

we are currently in the process of migrating Skype users on-premise to Teams including a Direct Routing Scenario. Part of our setup are call groups containing operators that can take the call and the resource account assigned to that call group has a number assigned.  We have followed the article Manage Ressource Accounts and everything works as expected except that the incoming call always has the Caller ID "anonymous" (see screenshot below). As soon as an operator takes the call the correct number will be displayed.

First I thought that this as to do with the Caller ID Policy blocking the incoming Caller ID but we have only one org-wide (Global) policy in place and that is set to not block the ID. I also created a user Caller ID policy and assigned that to the resource account without any change.

Has anyone an idea how to get the correct Caller ID displayed?

[#2]

The issue has been resolved together with Microsoft Premier Support.
The root cause was the source Caller ID not being in E.164 format. Our PSTN "Sipgate" does not send Caller ID's in this format, the country code e.g. +49 was always missing. Therefore we needed to configure our SBC to manipulate the number from e.g. "030123456" to "+4930123456".

Strange is that this was never an issue when directly calling a Teams user, only when a resource account was called and in turn a call group.