Firstly we need to configure the SIP Trunk between the PBX (Asterisk) and AudioCodes. Post that you need to configure the rules in the AudioCodes SBC to route the Three Digit Calls to PBX (Asterisk). Excluding the 911 calls.
You can always test the rules if that is converting the same in the following location 1. Teams Admin Center > Dial Plan > Normalization Rules.
You can test your normalization rules if that is working or not. Let me know in case you need any additional information's.