Area Code 301

You can increase your connection rate up to 30% by dialing from a local number.

Local Presence by Tenfold gives you one-click access from your existing phone system to a local number in the US area code 301 and more than 200 others.

Reach out to customers in Rockville, Silver Spring, Bethesda, Gaithersburg, Frederick, Laurel, and Hagerstown.

Source: Wikipedia