AUGUSTA – The wireless service provider T-Mobile USA Inc., said Friday it plans to open a new customer service center in Oakland in time to make calls next summer. It eventually could employ 700 people.

Maine advocates of the project said T-Mobile plans to invest more than $17.5 million in equipment and facilities and that the 700 or more jobs would carry a median annual salary of $35,000.

The regional impact of payroll alone was pegged at more than $16 million annually.

T-Mobile, which plans to begin hiring new employees in the spring, said the facility will help support its customer base of more than 16 million customers.

“Our customer service employees play a vital role in our company’s success,” Sue Nokes, T-Mobile senior vice president of customer service, said. “The culture and residents of Maine are very much service-oriented, which is a perfect match with T-Mobile’s values.”

The company said the 77,000-square-foot facility, to be located in the FirstPark development, would be a joint effort between T-Mobile USA, Holder Properties and The Staubach Co., Maine & Co., Gov. John Baldacci and the Central Maine Growth Council.

“We’re going to put out the clarion call for jobs,” said Baldacci, who views the project as evidence that the Pine Tree Zone business incentive initiative works and that there are benefits to be had from regional economic development.

The governor, who cut short his participation in a European trade mission to come back to Maine for Friday’s announcement, returned to the State House after the news conference at Colby College in Waterville.

The state Labor Department reported Friday that Maine’s seasonally adjusted October unemployment rate was 4.6 percent, down slightly from 4.7 percent in September and below the national October rate of 5.5 percent.

Officials said the Augusta-Waterville labor market has an existing labor supply of around 1,900 employed and unemployed telemarketers, customer service representatives and order clerks.

Credited with a key role in securing the new business was Maine & Co., a private nonprofit corporation that works with out-of-state companies considering locating in Maine.

The Baldacci administration said T-Mobile could qualify for more than $5.2 million in employee tax increment financing benefits over 10 years, and may also be eligible for business equipment tax reimbursement for up to 12 years and sales tax exemptions on machinery and equipment purchases for 10 years.

The state also is prepared to commit up to $840,000 in training funds, officials said.

Based in Bellevue, Wash., T-Mobile USA Inc. is a member of the T-Mobile International group, the mobile telecommunications subsidiary of Deutsche Telekom AG.