The SIMs are tri-cut, a mini SIM which is scored to allow you to break out a micro or nano sized SIM from it. Ting says that the GSM service is working well with the only known issues being that making international calls and international roaming are not available yet
Ting's plans and pricing are the same for both CDMA (Sprint) and GSM (services). Rather than having monthly plans with unlimited talk and text and varying amounts of data like most other carriers, Ting users are billed for separate tiers of voice minutes, texts and megabytes of data. If you use up all the minutes, messages or data in one of your chosen tiers, Ting will upgrade you to the next tier for the current month only. You can disable these automatic updates by setting usage limits that cut off your taking, data or messaging for the rest of the month when the limit is reached. The table below shows the available tiers.
|Text Messages (domestic and international)||$0||100||1000||2000||4800|
|Cost||$0||$3||$12||$19||$29||1.5¢ per MB|
Data, minute and messaging tiers can be shared across multiple phones or users on the same account, family-plan style. A multi-line Ting account can have a combination GSM and CDMA devices on it with all them sharing the same pool of minutes texts and data.
Ting SIMs should work in any T-Mobile phone that hasn't been reported lost or stolen or blacklisted for non-payment or any unlocked GSM phone that supports T-Mobile's bands. You can check if a phone is clear for activation using Ting's online checker. I expect far fewer issues with phones being rejected over payment issues on GSM than with the current mess that is Sprint MVNO activation.
Related: Prepaid Operator Profile: Ting
Source: Ting Blog