"Wireless Interference Detected" voice prompt from SS system.

For the last couple of weeks my SimpliSafe system has started alerting me via the voice system stating "wireless interference detected". I've had the system for a few months and I've never experienced this issue before. I contacted support via the technical support hotline and I was told to move my base station closer to my wifi router (AT&T Internet provider). The base station is already in the same room as the router (maybe 3-4 feet in distance between the two) so the tech support person said it should be near a window (it's about 2 feet from the window). When I asked if there is a way to assess what might be causing the interference I was told he would need to talk to a supervisor and put me on hold. After waiting nearly 10 minutes on hold I hung up. Does anyone have any suggestions? It's quite annoying and unnerving hearing a loud voice at 4AM saying "Wireless interference detected". We have not added any new wireless devices in our household and I had no problems in the first few months of having the system. Why would this start happening now? Any suggestions?