Look at what she's doing, she's expressing her right to talk to guys on the phone. She does it when you're not around right? So what, that's better than doing it when you ARE around. She mentions is so you don't be a loser and get all jealous and insecure about it. If you do then you're asking for it.
She has her right to talk to guys, what just cuz you two are dating that mean she can't talk to them or hang out with them? think about what that shows to her that you tell her that you have "problems" with her talking to these guys or seeing them. She gonna think you have some insecurity that something will HAPPEN between them and because of that she just might try something to.
Others have a good point in that she SHOULD respect you, but where is her fault? For having guys talk to her? ANd like her? Be happy you have a girl that guys like, don't be a p*ss and lose what you have then.
Then this is what you need to do, see how much this is gonna bug you. If you can take it further and find girls to talk with on the phone and such and she expresses a problem with it. Then u need to say something like "I thought we were ok with this? I have no problem with you talkin to guys, I mean SHOULD I be concerned?" most likely she'll say no. If it continues to bug her and she wants you to not talk to them, ask why. Then with that tell her that then I guess she should give it up too. If she don't budge, then that's up to you what you want to do next.