When your handset M25, M65, M70, M80, M85 or M90 shows the "Insufficient capacity" error, it is because the base station reached the maximum amount of simultaneous calls it can handle. 

The maximum number of calls per base station depends on the base station type, the operational mode (single or multi-cell), the codec used and whether SRTP is enabled or not.



 Snom M300  Snom M700/M900 (single cell mode)  Snom M700/M900 (multi-cell mode)
Max. narrow band calls (g711, g729*, g726) 10 8
Max. wide band calls (g722) 2 5 4
Max. calls with SRTP auth. enabled** (g722, g711, g729, g726) 2 5 4


Please note that for example if you add 5 handset in a PBX ring group every call to such group will use 5 concurrent calls.


IMPORTANT NOTES:

* using g729 with M300 has a known limitation: the maximum number of concurrent calls between handsets registered to the same base is only 4. 

** the reduced limit of concurrent call related to the SRTP authentication is applied when SRTP authentication is enabled in one of the configured SIP servers, so if you don't need SRTP authentication, please make sure to disable SRTP authentication on all SIP servers.