U.S. wireless carriers T-Mobile and Sprint have made progress in negotiating merger terms and are aiming to successfully complete deal talks as early as next week, people familiar with the matter said on Thursday.

T-Mobile majority-owner Deutsche Telekom and Japan's SoftBank, which controls Sprint, are considering an agreement that would dictate how they exercise voting control over the combined company, one of the sources said.

This could allow Deutsche Telekom to consolidate the combined company on its books, even if it does not have a majority stake in the combined company, one of the sources added. Deutsche Telekom owns more than 63 percent of T-mobile, while SoftBank owns 84.7 percent of Sprint.

Deutsche Telekom and T-Mobile are also in the process of finalizing the debt financing package they will use to fund the deal, the sources said.

There is no certainty that a deal will be reached, the sources cautioned. The companies came close to a merger agreement in November before SoftBank's chief executive officer, Masayoshi Son, pulled out of the talks at the last minute.

The sources asked not to be identified because the negotiations are confidential. Sprint, T-Mobile, Deutsche Telekom and SoftBank did not immediately respond to requests for comment.