Hey y'all I need some help figuring something out.

When a passenger is in the front and talking on a cell phone.. the person on the other end is getting a clicking or tone at regular intervals.
I'm assuming this is because of the passenger occupancy detection system with the three sensors.

What is the solution to keep the cars occupant system working properly and not have cell phone interference?
So far we put our hand over the phones mic but its hit and miss.

Thanks in advance for any advice!