New SimpliSafe system accidentally connecting to telephone

I have been corresponding via email with the Customer Service department about a problem i am having with my week-old system.  Every hour I get a "low battery" audio message.  I have followed all sorts of advice, with no solution.  Finally in desperation I started disconnecting all my sensors - two motion sensors and four door sensors - and I still got the same error message - WITH NO SENSORS CONNECTED!  I then realized that the low battery message was not coming from the base unit - it was coming from my telephone!  I have a Panasonic KX-TGF574, which is apparently interacting with the SimpliSafe system (and driving me nuts)!  Can someone give me directions on how to eliminate this problem?  

Thank you!  Dave Finton
davidtrpt@sbcglobal.net