MetroPCS' (NASDAQ:TMUS) wholly owned subsidiary MetroPCS Wireless plans by March 19 to close two separate private offerings, each of $1.75 billion in senior notes, due in 2021 and 2023.

The 2021 notes have an interest rate of 6.25%, while the 2023 notes have an interest rate of 6.625%. The proceeds will be deposited in a segregated account and kept in cash or cash equivalents, the company said.

If MetroPCS' proposed merger with T-Mobile USA is completed, MetroPCS Wireless intends to use the proceeds to repay outstanding amounts owed under its existing senior secured credit facility, to pay liabilities under related interest rate protection agreements, to pay related fees and expenses, and to use the remainder for general corporate purposes.

If the merger is not completed on or before Jan. 17, 2014, the notes will be subject to a "special mandatory redemption."

MetroPCS shareholders are set to vote on the merger April 12. Thus far, a waiting period required by U.S. antitrust laws has passed without objection from the Justice Deparatment, but approvals from the FCC and the Committee on Foreign Investment are still pending.