4452d530_able___FreeSWITCH___Confluence__Description
[ITU-T Q.850 Code] 111 [Enumeration] PROTOCOL_ERROR [Cause] protocol error, unspecified [Q.850] [Description] 
This cause is used to report a protocol error event only when no other cause in the protocol error class applies.
Hangup Cause Code Table - FreeSWITCH - Confluence
Description