I have UCM 7.0 and Cisco Unified IP phone 7965G. Whenever I dial some external number I get intermittent beeps during the conversation. Both parties listen to that beep and it comes randomly i.e. sometimes after 30 seconds and sometimes after 2 or 3 minutes.
I checked on Cisco website, they say it might happen if call monitoring or call recording is enabled. I am not using any call monitoring and recording.