Thank you for your post although I'm sorry to hear about the problems you've had calling this particular number.
If you are able to call all other numbers OK this would indicate that this may be a problem on the receiving persons side. Have you tried calling this number from an alternate phone to see if you experience the same problems?
I've rang from another phone and had no problem. Thought it maybe landline but rang a virgin landline and had no problem. I really need this sorted as it's my doctors and only just came out of hospital. Ant other ideas please