Sprint, the fourth-place mobile carrier in the United States, is struggling big time to convince customers to switch from its rivals. In an attempt to attract more people to their network, the company is offering huge discounts on their mobile plans, undercutting Verizon, AT&T and T-Mobile by 50 percent in most circumstances.

The promotion is specifically targeting the plans of its rivals: customers who switch to Sprint can get the same type of plan they're currently on, but at half the cost. For example, if you're currently getting 6 GB of data through Verizon for $80 per month, Sprint will offer you the same data allowance for just $40 per month if you switch to their network.

Sprint is running the promotion from this Friday until January 7th, 2016, and every rival plan – except for T-Mobile's $95 per month unlimited data plan – is eligible for the half-price deal. For those on T-Mobile's unlimited plan, Sprint already has a $70 unlimited offering that might tempt you across.

While the discounts do sound quite good at first, there are some limitations to the way Sprint is matching the plans of its competitors. The company is not offering any sort of data rollover, which you currently get on AT&T and T-Mobile, and they're also not matching T-Mobile's unlimited video and music streaming offering.

Unfortunately the discounts do not apply to existing Sprint customers: you'll need to be switching from Verizon, AT&T or T-Mobile to get a half-off deal. Customers that do switch will have the discounted pricing locked in until January 8, 2018, although you don't need to sign a two-year contract to get a half-off plan.

And if you're thinking of switching but don't want to pay the typically-expensive switching fees, Sprint is willing to pay them for you (up to $650) provided you turn in your current phone. Of course you will have to use Sprint's network, which might not have great coverage or the fastest speeds in your area, but the pricing of the promotional plans is certainly very attractive.