This is a carrier well-know effect after the big adoption of smartphones around the word.

As we explained in previous sections, each time the network decides to move a handset from one state to another is needed to reestablish channels and starts a negotiation between the network and the handset with the signaling protocol.

Since nowadays handsets are sending keep-alives to maintain their connections opened, the effect is that the handsets is continuously changing from one state to another producing a lot of signaling in the network and also consumes a lot of battery resources.