Me personally I believe every character should have a different phone number due to the fact me being Jose Chambers or you being who you are you are probably getting unwanted phone calls by people the current character you are on doesn't know, meaning that you can never meet any new people or take any new persons phone number down because they will already have it down as your other character.
If this were to be changed as to where every character had a different number, it would stop people from metagaming and or stop the phrase "sharing a phone with my cousin".