The 240 area code is a crucial component of Maryland's telecommunications infrastructure, especially in the western and southern parts of the state.

Introduction as an Overlay: The 240 area code was introduced as an overlay to the existing 301 area code. This implementation, which began on June 1, 1997, was designed to provide additional numbering resources due to the exhaustion of available numbers in the 301 area code. The overlay approach allowed existing 301 subscribers to retain their phone numbers, while new numbers could be assigned either the 301 or 240 area code.

Geographical Coverage: The 240 area code, along with the 301 area code, covers a significant part of Maryland, including western and southern regions. It encompasses major areas such as parts of Montgomery and Prince George's counties, which are in close proximity to Washington D.C., and extends to the more rural and western parts of the state, including cities like Hagerstown and Frederick. This area represents a mix of urban, suburban, and rural landscapes, reflecting the diverse demographic and economic composition of the region.

Adoption of Ten-Digit Dialing: With the introduction of the 240 overlay, ten-digit dialing became mandatory for all local calls within the 301 and 240 area codes. This requirement, which necessitates dialing the area code followed by the seven-digit phone number, aligns with the standard practice in regions with overlay area codes across the United States. The shift to ten-digit dialing was essential to manage the growing number of phone users and the consequent need for more telephone numbers in the region.

These facts about the 240 area code highlight its vital role in supporting the telecommunications needs of a substantial portion of Maryland. By providing additional numbering capacity and facilitating the transition to ten-digit dialing, the 240 area code ensures that the region's communication infrastructure can keep pace with its growth and evolving needs.