alright im just gonna lay out what the phone was in the comic and you will understand the "point " of the phone, but i completely agree the phone does not belong in the show whatsoever.
Comic scenario:
Govenor over ran the prison, rick and his group fight them off but the fences go down and the ultimately have to flee, lori carrying the baby gets cut down in the fight, Rick notices but grabs carl and runs like hell.
Andrea, dale, glen, maggie, the twins are all back at hershels farm.
The group is split up and carl and rick are alone with just a bag of provisions between them.
They wander into a neighborhood and find a house that is relatively safe by standards of the time.
Rick at this point has, lost his hand, been shot at and is on the run, at the house rick falls into a fever and passes out for days, carl watches over him with a gun pointed at him.
Carl nurses his dad back to health, but rick does not seem quite right, he hears the phone ring
rick and the people on the phone talk, the show literally lifted the dialogue verbatim from the comic, except for the whole part where rick gets on the phone for a third time and he asks who it is since it is someone different and its lori. this leads to rick carrying around the phone and talking to lori who is just a manifestation of his slipping sanity.
Its actually a very effectual plot device in the comic due to the isolation of carl and rick at the time, and the fact they are living on the edge of death, and it resolves itself later on, but in the show it had absolutely no place, just the writers trying to shoehorn in a piece of the comic in order to make the comic fans feel better, they are honestly falling so short on how awesome this season could have been.
The govenor was such a badass in the comic that kirkman went and wrote a whole novel about the guy