After joining ID when i inserted  the sim I was faced with the message that my number cannot be used by facetime and imessage. I then tried an esim and this was the same. I contacted Apple support who were very helpful. They confirmed my number was not blocked at their end (which can happen if you number has been reported for spamming. They then went through everything with me. (Most of this was the solutions already posted on this forum which I had already tried to no avail). I was then told to switch imessage and facetime off in settings and leave off for a minimum of 24 hours. On switching back on both imessage and facetime 24 and a half hours later my number was instantly recognised and imessage and facetime worked perfectly. (You can use your phone in the 24 hours just without facetime and imessage).

Hope this helps anyone having the same problem I had.