I have integrated CUC with CUCM over SIP. If the call is not answered in 10 seconds, it will reach to voicemail. From internal extensions, its working fine. However if i dial from PSTN to Direct number which is transferred to extension, call is getting dropped. Its not forwarding to voicemail. I have checked CUC port monitor, for PSTN calls its not hitting any port.
CUC and CUCM version - 11.5