Microsoft will discontinue support for sip-all.pstnhub.microsoft.com on March 1.
The DNS entry sip-all.pstnhub.microsoft.com currently still returns all IP addresses of the data centers used by Teams Direct Routing.
Instead of sip-all.pstnhub.microsoft.com, two network ranges should now be used:
The sip-all.pstnhub.microsoft.com will be used by anynode in all “Network Peer Whitelists” of the “SIP Transport” object to allow communication only with the returned datacenters.
TE-SYSTEMS plans to release an update at the end of January 2022 which will update the Network Peer Whitelists.
Those who do not want to wait for this update can make the changes themselves. To do this, the “Network Peer Whitelist” in the SIP Transport Object of each Teams Node must be supplemented by the two network areas. Afterward, you can remove sip-all.pstnhub.microsoft.com and the IP addresses of the datacenters, if they are still entered. Local IP addresses that are needed to use a Teams SBA must remain on the list.
Please do not forget to check if external firewalls are still configured to single Microsoft IP addresses. This must also be changed to 18.104.22.168/14 and 22.214.171.124/14.