To find your representative’s phone number, click here.  You can also call the U.S. Capitol Switchboard at (202) 224-3121 and ask to be connected to your Senators' and/or Representative's offices.

Calls to Congressional offices are handled by legislative staff, rather then the Members themselves. When you call, ask to speak with the person who handles your issue. The staff are usually very knowledgeable and Members relies on their advice in taking positions on issues. 
 

Identify yourself and then provide a brief message such as, “Please tell Senator/Representative (name) that I support/oppose (S._____/H.R.________).”   

Briefly state the reason for your position and ask if the Senator or Representative has decided whether to support or oppose the legislation. Keep it cordial. You may wish to re-state your position, but do not argue at length.