GXP1615 IP Phone unable to receive incoming calls



We are using 150 GXP1615 IP phone to our Client factory site which register with there office UCM6204 over ipsec vpn .
But when those phones are keep idle mode for a long time then those phones are unable to receive incoming calls, we already change the NAT Traversal Mode has set to keep alive /auto/no the keep alive settings in to our UCM6204 extension, also but the result is same .

Please give me a solution for resolve the issue .


Ensure keep alive is as follows and VPN link is set to ALWAYS UP.


set the keep alive time to 15 seconds and make sure you have not activated the NAT


already set done the above setting and keep alive time 20 , but the result the same


which site sir , ucm or phone ??


I don’t understand what you’re trying to tell me, doing what I wrote on it?


I am asking you that which site we need to change the parameter . UCM or IP Phones ??


if you are referring to NAT it must be disabled on local extensions and on extensions via VPN