Apple and T-Mobile today opened pre-orders for the iPhone 5, a week ahead of the smartphone's official April 12th release. T-Mobile, the fourth largest carrier in the US, becomes the last of the big four operators to offer the iPhone, following behind AT&T, Verizon Wireless, and Sprint.

Last week, T-Mobile unveiled its new Uncarrier branding and smartphone plans, no longer requiring customers to sign up for a long-term contract. Instead, T-Mobile offers a 16GB iPhone 5 for $99 upfront with 24 months of $20 payments on its Simple Choice plan, or $579.99 in full, $70 less than an unlocked iPhone 5 bought direct from Apple. T-Mobile also offers the iPhone 4S, which costs $69.99 upfront with payments of $20 per month, while the iPhone 4 costs $14.99 plus a $15 monthly charge. T-Mobile says the older models will only be available in "select markets."

The iPhone 5 is compatible with T-Mobile's expanding LTE network and its "4G" HSPA+ networks. The carrier also boasts it is the only US mobile provider to offer nationwide HD Voice on the handset. The company is currently bringing preorders online, so keep trying if you can't process your order.