Communication breakdown

Invited to M's for dinner. I arrive, ring the doorbell, no answer. Phone, only answerphone. I'm standing there for about 15 mins, ringing every now and then, thinking I'll give it a few more mins more then go. The door opens, they'e been wondering where I've got to. 
Turns out the doorbell's broken.
Compensated by a wonderful meal, glad I waited!