What is happening is the called leg is not sending any RTP packets but the RTCP report interval is still running and if it does not detect anything for the configured amount of time it will end the call, which is why the calls were dropping after only 60 secs.
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Here is how I fixed it:
On CUBE run the following command:
router(config)#ip rtcp report interval [time in milliseconds]
router(config)#gateway
router(config-gateway)#timer receive-rtcp [value]
***INFO - The 'timer receive-rtcp' value argument (or Mfactor) is multiplied with the interval that is set using the 'ip rtcp report interval' command.
Also if you recieve this error,
"timer media-inactive dsp based detection is already configured and it takes precedence
unconfigure timer media-inactive to enable non dsp based detection to take effect"
you will have to disable the 'timer media-inactive' command
router(config-gateway)#no timer media-inactive
Example
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router(config)#ip rtcp report interval 12000
router(config)#gateway
router(config-gateway)#timer receive-rtcp 5
This will allow 60 secs before the call will be cutoff. 12000 msec x 5 = 60000 msec / 1000 = 60 sec
router(config)#ip rtcp report interval 60000
router(config)#gateway
router(config-gateway)#timer receive-rtcp 5
This will allow 300 secs or 5 mins before the call will be cutoff. 60000 msec x 5 = 300000 msec / 1000 = 300 sec
References:
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http://docwiki.cisco.com/wiki/Cisco_IOS_Voice_Troubleshooting_and_Monitoring_--_Media_Inactive_Call_Detection
http://www.cisco.com/c/en/us/td/docs/ios/12_2/12_2x/12_2xb/feature/guide/ftsiprtp.html#wp1039389
https://supportforums.cisco.com/discussion/11586206/call-drops-after-25-30-seconds-exactly-need-some-help-ccie-guys
