Recently I was asked by a client if it was possible to call a phone number and have it call their paging system. their paging system was an ALGO system that was compatible with Microsoft Teams SIP Gateway.
First, we went through the process of connecting the paging system to the SIP gateway. that was not a big deal and it went flawlessly. Then we assigned appropriate Shared Device and Calling plan license to the appropriate Resource Account. This all worked great, but the client did not want outside callers calling their building paging system. So I had to think a bit.
After trying things in my lab, this is the solution I came up with:
1. Unassign the Calling Plan license from the Resource Account
2. Open up the Resource Account in the Teams Admin Center and manually give the account a “fake” number in Direct Routing. In this case it was 2223334444.
Then I tried it out. I could dial 2223334444 and it connected to the paging system. I could also pick the paging system out of the GAL and connect that was too. However, the client wanted to use the old number to dial the paging system, because everyone was used to it. So I had to think a bit more. After a bit of time, I came up with a Dial Plan policy that translated the old number to the “fake” number for the paging system. The dial plan regex looks like this: .*3035551212.* and it translates to 2223334444.
Easy Peasy!