IP 4602 phones no dialtone

[slovic]

I am experiencing some problems with IP 4602 hardphones and IP Office 403 at customers site, and I hope that you could help me. The configuration on the site is as follows:
- 4 x IP 4602 hardphones are connected to IP Office 403 (software version 1.4 (22)) through LAN (via 2 network switches)
- Software used by IP 4602 hardphones is version 1.6
- IP Office control unit has static IP address
- All IP 4602 phones have static IP addresses
- VPN extensions are configured with static IP addresses in VoIP tab section.
Problem:
After the installation IP4602 phones worked well, but after a day IP4602 phones appear to be functional (there are date and user shown on display), but there is no dialtone (or any tone) and the phone could not be used. Following the reset of the phone, it work well for a while but the next day problem reappears

 

[MrIPO]

Do you still get no dial tone, even if directly patched to the front of the IPO ??

Can you do a DTE trace of the Loader, does the VCM present any errors when booting.

Can you post a H323 trace when the handset if lifted and you do not hear dialtone.