Bell Atlantic employees, also, have had to refresh some memories since the company began assigning the 240 area code in January, said spokeswoman Sandra Arnette.
But there haven't been a lot of calls, thanks to the Bell Atlantic's long preparation of customers, Arnette said.
The company spent about $2 million on a customer education campaign to ready folks for the assignment of two new area codes in Maryland, she said.
The telephone company switched from seven-digit to 10-digit dialing for local calls back in May 1997 to prepare for the area code "overlays" to meet demand for new telephone numbers, Arnette said.
With so many new numbers needed for fax lines, computer lines, second phone lines, multiple business lines and cellular phones, Bell Atlantic was quickly running out, she said.
It was decided that rather than carving the state into more geographic regions with their own area codes, both of the two current regions would be assigned a second area code, Arnette said.
The 301 area code region -containing Washington, Frederick, Allegany, Garrett, Montgomery, Prince George's, Charles and St. Mary's counties - would get 240 as its second area code.
The 410 area code region - encompassing the rest of the state - would get 443 as its second area code.
Running out of phone numbers with the 410 area code at a faster rate than 301 area code numbers, Bell Atlantic started giving out numbers with the 443 area code around the end of 1998, Arnette said.
The company estimates that the two overlays will supply enough numbers to last at least 11 years, compared to about seven years if the company would have made another geographic split, she said.
The 410 area was introduced in 1992, Arnette said.
Prior to that, the 301 area code was used throughout Maryland, she said.