@EddyAnk_2941679 With such little information, it's almost impossible to say exactly why.
Do your accounts show active sim and current Smarty plans?
Does Coverge checker show that you should have a signal? Does Network Status show any local problem?
Have you only just joined and activated? If so, it can take an hour or two before the system catches up.
Are your phones compatible with Smarty VoLTE protocol? See: https://help.smarty.co.uk/en/articles/8985136-checking-if-your-device-is-4g-volte-compatible
I hope you can see why your question is a tough one as it stands.
