You can call your phone company and ask for a service called "Call Block" (sometimes called Call Screening or Call Rejection). The service will allow you to block incoming calls from a specific number. The service is usually less than $10/month. If its a solicitor calling you you can add your number to the do not call list (as Kibe said above)
You can block a phone number from calling you by using the do not call registry by dialing the number 1-888-382-1222, enlisting help from your service provider to stop the number from calling you or by using one o f the handsets specifications that are built in or you can download them to your mobile phone.