I have a iDCS28d on a 7100 that was sitting there giving out a triple beep at a very regular interval. Just a bit slower than the MW light. It was coming through the speaker and then the handset when off hook.

I thought it might be tied to a call back or msg notification, but it remained after I cleared all the messages.

In the end, rebooting the phone got rid of it.

Any ideas what the cause would have been?

-Will