Call queue not working when second person try to call to queue number

Hi antoonioo84, first of all I would suggest to setup the call queue in a supported way by Microsoft. Therefor you must request "Teams Phone System - Virtual User" licenses for your resource accounts. Ask your CSP, license vendor or request the licenses directly in the Microsoft 365 Admin Center -> Billing -> Licenses. The licenses a free of charge and at no costs for you.

Normally the SBC will route the incoming call to Microsoft Teams and the call queue service. So, I would first check the Call Queue settings. What are the settings for Call overflow handling? How many calls can be handled in the queue? What is the action to the callee when the queue is full? What is the wait time and what is the action for the last callee?

Do you have the option to create a syslog from the Audiocodes SBC and to post the SIP Call flow if necessary?