GSM unlocked cell phones have been catching on in the US for years. In the past year, more retailers are trying their hands at directly releasing unlocked cell phones to US consumers.

Although these phones aren't as awesome as a jailbroken iPhone or unlocked Galaxy S II cell phone, they offer something that other cell phones don't: a dual sim card.

A dual sim card adds to the versatility that unlocked cell phones already provide: instead of just switching between carriers as needed, you can have two carriers at once, with two separate phone plans.

This is great if one carrier offeres unlimited data or texts more cheaply than another, but if an entirely different carrier offers a great price on minutes.

Having an unlocked cell phone with dual sim cards is ideal for business travelers, who can more conveniantly switch plans when going between the US and another country—a great way to avoid the huge roaming and data charges that can accrue when travelling abroad.

Of course, unlocked cell phones do cast some wonder onto the future of the US cell market. When will major carriers catch on to the demand for unlocked cell phones? Will two competing markets emerge, an old and a new?

Weigh in with your thoughts below: