Thanks for your post and a very warm welcome to our Community Forum!
Sorry to see that you've been having this issue with your phone after a number port, is this an iPhone by any chance?
This is a problem I've come across with several iPhone users, it's a simple case of manually updating the mobile number on the device
Go into settings, select your profile at the top of the screen and the select Name, Number, E-Mails...you will be able to edit the mobile phone number to the one you've ported in and this should solve the problem for you. If this isn't an iPhone or this hasn't solved your issue on an iPhone do please get back to me and I'll take this into PM for you