why has her phone stopped talking to mine?

My friend and I have intermitent Text conversations and sometimes also
speak on our mobile telephones. My texts to her arrive with no
problems. However her texts to me, since January 2009, have not
arrived and if she trys to telephone me she gets the engaged signal.
She has no problems with any of her other friends. Do you have any
suggestions? Thank you, M. Steele

M. Steele
March 2009