Sorry if this is a derail, but: of course opposite-sex friendships and same-sex friendships are different
I bet you don’t “make a point” of meeting your female friends’ boyfriends and talking about these boys “in a positive way” in order to make it “clear to everyone” that you’re not interested in sex with your chums
I would feel totally different about a female friend my boyfriend developed over time at his job than say, if he sat down one day on the bus next to a girl and went home with her number. Unfair judgment, perhaps, but friendships developed in the second way or something similar would maybe seem similar to hitting on or picking up on a girl.
I didn’t say they couldn’t be friends, just that, obviously, they can’t be friends in the same way as same-sex friendships
Also, did you totally light up or leave the room when the other girl called, how long were you on the phone, was there any reason for the call, etc?? Realize there may have been may factors that caused your gf’s reaction.
Maybe your girlfriend later realized she’d overreacted too. She probably does feel jealous or controlling but maybe she’s willing to let reason and logic rule from now on, or calm her fears. I imagine lots of girls would feel a tad jealous if this same situation happened. Some, unlike probably most of the previous posters wives and gfs, may not have had the opportunity and time previously to deal appropriately with this type of thing. It sounds like it’s never come up between you(or potentially with another) so give her the chance to come to her senses.
Also maybe your change in behavior (starting to form female friendships) makes her question whether it could also be a change in thinking.
In the end though, you’ve really just got to talk to her.