In a test installation of Cisco Unity Express on ISE-CUE (C1861) router, voice view express has problems when working with remote Callmanager.
In the voiceview I cannot listen or record any messages, IP phone displays the following error:
"Authentication error. Report this error to your system administrator"
if my phone (CP7941G, sw SCCP41.8-3-3S) is at remote site.
If my phone is connected to a local Callmanager (version 5.1.3 too), voice view express works OK.
I have tested it with Cisco Unity Express version 7.0 and 3.2.
I have monitored the IP phone using wireshark packet sniffer.
When I ask IP phone to play recorded messahe, the phone sends authentication request to the CallManager (to 8080 port).
If the phone does not receive a SYN,ACK reply packet to his first SYN packet fast enough, it sends within 18 - 20ms,it send another SYN packet and does not wait for Callmanager response.
Is there any setting available to increase the SYN,ACK packet timeout on the IP phone?
Or should I use a different version of phone software?