Guys, regularly answering cell phone calls (especially from other women) while you are out together with your lady is a big no-no. A woman wants to feel that she's the full focus of your attention and will feel insulted and disrespected that you would take these calls right in front of her--especially if she already has told you that it bothers her. Your outside communications during a date should be limited only to emergencies.
If and when you get her back to your place at the end of your date, do not under any circumstances stop a make-out session to answer the your phone--in fact, just turn your phone off! Interruptions like this can really bring a potential evening of romance to a screeching halt.