Calls Drop after One Minute - Caused by Extension Max Call Duration(s)

Applicability

• Firmware version: Any
• Model: S-Series

Problem Description

The calls drop exactly in one minute once they establish successfully though the global max call duration(s) is set as 0 which disables the limitation.

Analysis

The PCAP log shows S-Series PBX sends out the BYEs to Phones which causes the call drop. There is only a brief hangup reason, Q.850; cause=16 which means Normal Call Clearing:

 https://support.sonus.net/display/UXAPIDOC/Q.850+Cause+Codes+-+Reference

Asterisk CLI log shows normal as well.

Fortunately, we find the extension max call duration(s) is set as the 60s which has a higher priority than global max call duration in General>Preference. This case teaches us to check the basic settings before everything.

Solution

Disable the extension max call duration(s) and the issue is gone.