T-Mobile is on stage at its "Boldest Moves Yet" event in New York City, where the US carrier just introduced a new strategy called Jump for phone upgrades. 

Jump would allow customers to upgrade to a newer device semi-annually. That's an enticing offer when compared to the traditional two-year upgrade policy at rival carriers Verizon and AT&T. So, how does it work? Well, with Jump, customers can upgrade their phones after six months of enrollment. The program allows them to upgrade affordably for just $10 a month (per phone). 

Specifically, beginning 14 July, customers upgrade twice every 12 months after they’ve been in the scheme for six months. A customer simply has to trade in an eligible, good working-condition T-Mobile phone at a participating store location to get a newer handset. In other words, T-Mobile customers will no longer have to wait or qualify for subsidised pricing to purchase a new handset.

Read: T-Mobile USA promises LTE-Advanced roll-out by end of 2013

To go along with Jump, T-Mobile has announced a 4G LTE expansion and a new unlimited programme for families. The carrier revealed its 4G LTE network, which debuted less than four months ago, now blankets 157 million people in 116 metro areas across the US. Major metropolitan include New York, Los Angeles, San Francisco, Chicago, Boston, Philadelphia, Dallas, Seattle, Atlanta, Miami, and many others.

As for the unlimited programme, T-Mobile will now let families have four phone lines with unlimited talk, text and Web and up to 500MB of high-speed data for $100 a month. And there's no credit check or annual service contract required.