Exchange Admin Center in Office 365 to allow voicemail messages from Teams Microsoft.
Create this rule:
1. Navigate to Exchange Admin Center > Mail Flow > Rules
2. Click on "Create a new rule"
3. Create a new rule that:
Name: Teams Bypass For Trend
Apply this rule if: "The message type is"> include the message type > "Voice Mail"
Sender's IP address is in the range
13.107.64.0/18
52.112.0.0/14
52.120.0.0/14
52.238.119.141/32
52.244.160.207/32
2603:1027::/48
2603:1037::/48
2603:1047::/48
2603:1057::/48
2620:1ec:6::/48
2620:1ec:40::/42
latest Teams IP addresses - https://docs.microsoft.com/en-us/office365/enterprise/urls-and-ip-address-ranges
4. Do the following...
"Require TLS Encryption"
Then
Chose a mode for this rule: Enforce
Tick
"Stop processing more rule"
5. Click Save
Move above the ONLY accept Mail from Trend Micro)
