The 301 habit is proving difficult to break.
Almost two-thirds of all calls made from within the state to numbers in the new 410 area code are still being dialed using the old 301 prefix, a study by the Chesapeake & Potomac Telephone Co. shows.
That's despite the fact that 99 percent of C&P's business customers and 92 percent of residential customers know that the eastern half of the state officially and forever entered the domain of 410 on Nov. 1.
"In other words, while nearly everyone knows about the new area code, our studies show that many people aren't dialing it yet," said Dave Pacholczyk, a C&P spokesman in Baltimore.
When asked why they didn't use the new area code, some people said they just couldn't seem to shake the 301 habit, C&P said. Others said they either had no reason or no occasion to use 410.
The day 410 was introduced, about 13 percent of calls placed to the eastern half of the state were dialed using the new area code.
As of Jan. 14, 38 percent of all calls within Maryland to 410 were dialed using the correct area code.
The numbers were substantially better for calls that originated outside the state. About 70 percent of those calls were made using the right area code, C&P said. Those percentages were apparently helped by the fact that operators give the 410 area code to callers.
Other states with varying area codes have had to electronically block calls to get similar results, Mr. Pacholczyk said.
In Maryland, that won't happen until Nov. 1, 1992. On that date, calls to the 410 area code that use the wrong area code will be blocked and a recording will tell callers to redial using the correct area code.
But C&P is hoping a lot of people can break the 301 habit before then.
"We're encouraging all customers to learn to dial correctly now, so they can save themselves some time and aggravation this fall," Mr. Pacholczyk said.