Interesting news from a T-Mobile forum discussion today, as it seems users are starting to get free tethering on their prepaid plans. While the freebie was originally spotted by a Cyanogen user who assumed it was due to his new ROM, others quickly chimed in noting they were seeing the same functionality.

Their $70/month plan is showing — via the T-Moble “My Account” app — 2.5GB free tethering monthly. Writer Andrew Martonik from Android Central notes his app shows 100MB free tethering, which is half of the allotment T-Mobile is now giving for tablets. He and I happen to have the same prepaid plan ($30/month, unlimited data), but a conversation with T-Mobile yielded me much different results.

In an online chat, and later a phone conversation, T-Mobile notes my prepaid $30/month plan is eligible for 5GB free hotspot tethering monthly. It’s worth noting that the plan offers 5GB of data at top speeds before throttling down. Normally, when tethering was activated, I’d need to call T-Mobile and pay $15/month for the pleasure. Now, it simply works without incident.

This could be phase four of the “Un-carrier” approach, or just a new feature they haven’t yet announced. Either way, it makes prepaid much, much more attractive. Spending a lot less versus a postpaid plan was already enough to keep us around, but free tethering is just going to make it that much better.