Apple

it has been about 2 months since i had my iphone 15 pro and this message is displayed, “you must have a sim associated with an apple device for to be used for imessage and facetime” i have tried everything on the internet. other people using the same carrier and same plan have no problem activating it. i even contacted the apple costumer care and no solution at all. Is there anyone else with this issue and any solution to this problem? I have tried everything suggested on the apple forum including a full reset. nothing seems to work. The carrier is NEPAL TELECOM in NEPAL. The sms send and recieve all work. just the face time and imessage arent activated… i desperately need a fix