They’re just “friends”

So there’s this girls name that always pops up on my boyfriends phone. Come to find out, they were fw eachother but they’re friends before anything. Whatever right, I leave it, I decide to trust him and just let it be. But they constantly FaceTime/talk on the phone/text (not in front of me, I peeped his call log) but he keeps insisting on them being just friends. Sounds sus to me and I don’t really fw it. Especially the fact that they used to fw eachother. I told him this and he claims he doesn’t talk to her anymore but I know he is and this girl knows about me. I’m really not the type to ask a guy to block a female or tell him he can’t be friends with a girl but I feel like it’s getting to that point, I don’t want to come off jealous or insecure because I’m far from that. I just kind of want to see if he would block her if I asked him too. It’s a respect thing. If he asked me to block a guy with valid reasoning I would. But I can’t 100% percent say he would do the same. I really don’t care if she’s blocked or not I just wanted him to stop communicating with her and it seems like he can’t do that so I guess I just want to test him?? Idk if this makes sense, hopefully it does. If he says he won’t, obviously I’m done with him I’m just super curious as to if he would or would not do it. Has anyone ever had a problem like this & what did you do?