If Send Extra Leading Character In DisplayIE is unchecked when the Primary Rate Interface (PRI) Protocol Type is DMS-250, the Media Gateway Control Protocol (MGCP) calls receive a busy signal.
In addition, this disconnect cause code can appear in the debug isdn q931 command output:
DISCONNECT pd = 8 callref = 0x9172Cause i = 0x82E5 - Message not compatible with call state or protocol error threshold exceeded.
In order to fix the problem, complete these steps:
Refer to these documents for more information: