4452d530_able___FreeSWITCH___Confluence__Description
[ITU-T Q.850 Code] 41 [SIP Equiv.] 503 [Enumeration] NORMAL_TEMPORARY_FAILURE [Cause] temporary failure [Q.850] [Description] 
This cause indicates that the network is not functioning correctly and that the condition is not likely to last a long period of time; e.g. the user may wish to try another call attempt almost immediately.
Hangup Cause Code Table - FreeSWITCH - Confluence
Description