How do I stop this friend pestering me with phone calls?

I dont want to fall out with her but shes not really a close friend anymore and ive been ignoring her phone calls for a week because I feel like it and hoping shed get the hint that I cant be bothered but she has rang me 3 times today,I dont know what to say because its clingy,she knows I dont have loads of friends and I am sometimes a loner but I dont need sympathy for that.