Of the sea of MVNO’s piggy backing on the Big 4’s networks, Ting presented an interesting concept: pay only for what you use in a given month. Of course, its biggest shortcoming was that it operated on Sprint’s network. Not exactly the easiest pill to swallow.

For those that were interested in giving Ting a shot but were turned off by the prospect of having to put up with Sprint, they’ve officially announced that their new GSM service is officially in open beta. Their GSM SIM cards — which operate on T-Mobile’s network — run about $9 and fit into a variety of devices using built-in SIM adapter.

Ting’s service charges you $6 for each connected device, and you pay only for the amount of minutes, text messages, and data you use in a given month. Here’s the pricing rates:

Keep in mind that while in the open beta, international roaming and long distance aren’t fully operational. Also, when bringing a T-Mobile phone over to Ting, the phone will need to be paid off first (but not unlocked). However, those looking to bring an AT&T device will need to make sure it’s been unlocked beforehand, something that shouldn’t pose too much of a problem given recent developments.

Anyone thinking about giving Ting a shot?