Washington ? Starting next week, millions of people in small cities and rural areas will be able to take advantage of federal rules allowing cellular users to keep their phone numbers when switching to new wireless carriers.

The rules first went into effect last November in the 100 most populous metropolitan areas.

On Monday, the Federal Communications Commission will expand its “number portability” rules to the rest of the country, which includes Lawrence.

Consumers also can transfer a number from a traditional landline phone to a cell phone if the exchange — the three digits following the area code — falls within the same geographic area.

The extension of the rules is not expected to be met with an enormous surge in requests for transfers since most of the country has already had the opportunity to switch.

The FCC estimates the rules covered about 70 percent of the population when implemented Nov. 24 in the top markets.

For the remaining 30 percent, making the switch should be a mostly smooth process, says K. Dane Snowden, head of the commission’s Consumer and Governmental Affairs Bureau.

“The majority of carriers are ready,” said Snowden, though he added, “We do anticipate some hiccups initially in this process.”

For some carriers, he said, delays in transferring accounts were likely.

The FCC set a goal that the transfer from one wireless company to another should take only about 2 1/2 hours. Many consumers, however, complained early on that transfers were taking days, and in some cases weeks.

The FCC logged 2,400 complaints in the first month after the rules took effect last year. AT&T Wireless received the most complaints and blamed a software glitch for the problems.

Since then, complaints have slowed sharply, with only about 400 for April.

About 2.6 million wireless customers have switched to new carriers since Nov. 24, according to the FCC. More than 217,000 cut the cord entirely, moving from a traditional landline phone to a wireless one. A smaller number — 5,400 — went from a cell phone to a landline phone.

A trade group for wireless companies expressed confidence that cellular firms would be ready to handle the additional transfers next week.