T-Mobile boasts record August as it preps for iPhone 5S, 5C

T-Mobile had a good summer. And it hopes the iPhone 5S and iPhone 5C will keep its momentum rolling in the fall.

T-Mobile Chief Marketing Officer Mike Sievert told CNET in an interview on Thursday that he believes the company posted a record market share in total gross post-paid customers in August. In other words, out of the total number of new customers who signed up for service with any wireless carrier, T-Mobile snagged the most that it has ever grabbed. Considering T-Mobile added more customers than AT&T, Verizon Wireless, and Sprint combined in the second quarter, it's a safe bet it led the way again in August.

"Obviously, there's momentum," Sievert said.

T-Mobile believes the coming iPhone launch, scheduled for September 20, offers the company a chance to nab market share away from its larger rivals. New, high-profile devices give the customers a reason to switch carriers or get out of an existing contract.

"The product launch represents a fantastic opportunity for T-Mobile to win switchers and gain mind share," Sievert said.

This is the first iPhone launch day for T-Mobile, which just began carrying the iPhone 5 this year -- months after every other major carrier.

T-Mobile is making it easier on the wallet on an upfront basis for iPhone buyers. Customers don't have to put any money down on the iPhone 5C, although they will have to pay $22 a month for two years to pay off the device. The iPhone 5S will cost $99 down and $22.91 a month for two years.

T-Mobile offered the iPhone 5 at the same $99 price when it launched, but later raised the price. Sievert confirmed the prices were temporary, and would likely be gone in a few weeks.

As with other phones, T-Mobile doesn't require a contract, but requires the customer to pay for the device in monthly installments (customers who don't meet certain credit requirements would have to pay a much higher upfront price for the device). Likewise, the company touts its JUMP early phone upgrade program as an opportunity for customers to move to either iPhones.

The no-contract model and early upgrade program are part of an aggressive slate of measures T-Mobile has taken to win back customers, who for years had fled the company because of poor service. The company has improved its network, expanding its 4G LTE coverage and HSPA+ coverage, which it also calls 4G, and bulking up its sales staff. A T-Mobile executive said the company had personnel requisitions for 3,500 new positions, much of which would be in retail.

Andrew Sherrard, a marketing executive at T-Mobile, confirmed that HD Voice, a feature unique to its iPhone 5, would be returning in the iPhone 5S and iPhone 5C.

Sherrard believes T-Mobile is ready to handle the launch day and expects big demand for both iPhones.

"We have great pent-up demand out there," he said.

Watch this: Apple takes the wraps off the iPhone 5S

02:01