Hundreds of thousands of consumers have switched mobile phone providers since new federal rules went into effect allowing them to keep their cell phone numbers when they change carriers. But there’s a problem: Users are finding technical glitches and delays in making the number transfers, The New York Times reported.

Customers have had to wait several days for their old numbers to work on their new phones, and some have waited more than a week – even though switching a number is supposed to take only a few hours.

In fact, according to people in the industry, the automated computer processes that are designed to carry out the number switching have been failing about 50 percent of the time – making it necessary for the wireless carriers to check the customer data manually, a time-consuming task.

Although delays at AT&T Wireless appear more pronounced than at other carriers, all are facing similar problems. According to reports from analysts and consumers, most switches have taken longer than a few hours, the goal regulators hoped carriers could achieve.

A carrier signing up a competitor's customer has to enter that customer's name, address, Social Security number and other data into its computer system, making sure that it matches data from the transferring system. If the data does not match up, the two companies must then manually verify the information, a process that can take days.