He may have slammed it on the receiver.
So Sheila’s is going crazy with a gun, Neville decides to let her get on with it, phones Jeremy up to tell him to come over and help, doesn’t want to involve the Police, hears Sheila (was she shooting away at this stage) attacking June throws the phone on the hook, it luckily cancels the call between Jeremy and himself, stops Jeremy ringing back, the phone falls onto the table making it look like it’s off the hook, he runs upstairs into a ambush of fire from Sheila? Have I missed anything out at this stage?