FaceTime activation on multiple iPhones using same apple ID

I bought a second phone and a new line from a different operator in a different country. I set up the new phone with the exact same Apple ID as the old one. Everything is working well except for iMessage and FaceTime.

the phone detects the new number but every time I chose it to send/receive messages or calls from/to I get stuck in the activation phase endlessly. I tried all the suggestions I found from restarting, to toggling on and off services, nothing works.

when sending SMS from old phone to new phone it goes out but never reaches the new phone. And when sending from new phone to old phone, the sms fails to send…

any suggestions?