Clicking noises and complete Loss of all background noise

My boyfriend and I sleep every night on our cell phones, with our work were never home. Recently only on the evening calls his phone continuously makes whomping noises off and on up until he falls to sleep. Also, I can hear all his background noises, mostly his t.v but everytime after the noises every bit of his background noise stops. Almost like he is muting me although he denies that. Both things stop once he falls to sleep. I only have this happening with his phone, no one else's I speak to.

What could he be doing to cause these two things? I thought maybe he is sending texts or receiving texts? The whomping when he is pressing the letters and the silence when he sends? Any clarity to this is greatly appreciated. It really is driving me crazy.