Weird cellular connection problem with my Qin F21 pro

[u/Varap1]

Hello!

So I bought my Qin F21 pro 3 months ago, and since I got it, I have had an issue with calling and receiving calls. Some people can call me, and I can call them, but some can't.

For example. My mom (Samsung A52) can call me, and I can call her, but my friend (iPhone 14) calls me and gets a notice that I'm unavailable, like I have airplane mode turned on or my phone is turned off. When he calls me, I will lose cell connection for a few seconds and then get it back. If I try to call him, I will instantly get a pop-up saying that the service of my mobile phone isn't available, then get a message that I'm synchronizing my contacts on my SIM card, and then regain connection. If I call him in a minute after getting my connection back, I will be able to call him like normal.

This isn't an iPhone vs Android issue either, since I can call and receive calls from my brother (iPhone 12) and can't call or receive calls from my dad (Samsung S23). Noir, is it a problem of how old the phone model that is calling me is, since I can call and receive calls from a friend who has an iPhone 17.

I have checked with my mobile carrier, and there isn't a problem with my SIM card (like if it was damaged or my cell plan wasn't paid or active). So it has to be something with the phone I just don't know what it is.

So in short. Seemingly at random, some contacts are unable to reach me since I'm "unavailable," and I have to call them at least twice to be able to reach them, while others can reach me, and I can call them with no issue at all.

Thanks in advance for the help.

[u/Outrageous_Name_6196]

What country are you in?

What service are you using?

[u/Varap1 → u/Outrageous_Name_6196]

I'm in Slovenia and I use Telekom