Can't call specific number

[Meph]

I'm unable to call a specific number for the last few days - worked fine before that. Says number not recognised but I can call it from other phones without difficulty and I can call other numbers without a problem. I'm not blocked by them (I've checked). They can ring me. We can exchange texts. They're with Virgin. I'm using a Fairphone 4. Any suggestions?

[Three_Stacey]

Hi @Meph thanks for reaching out to us here on 3Community. This is a weird one, do you know if they recently moved to Virgin? If so they'll need to reach out to Virgin. 

If they haven't recently moved please PM us with your name, number, full address and date of birth. I will also need the number you're trying to call and the time and date of your latest attempt.