While MetroPCS may not exist for much longer as a standalone company thanks to the proposed merger with T-Mobile, that isn't stopping the country's fifth-largest carrier from pushing out new services. Today, the company announced Joyn, a message, video chat, and syncing service based on the Rich Communications Services standard. MetroPCS says it's using RCS to power four categories of services, many of which will sound familiar to most smartphone users: contacts presence, enriched chat, content sharing, and Wi-Fi / video calling. Probably the most useful will be "enriched chat" — this is essentially a competitor to iMessage that will include delivery confirmation and message composition alerts. The big plus here is that these messages won't count as standard SMS messages, just like iMessage. Wi-Fi and video calling are fairly self-explanatory — users can place voice and video calls when connected to a Wi-Fi network, making this a decent proxy to FaceTime.

Joyn's "content sharing" features also sound reasonably fun and useful, though hardly essential. MetroPCS says you can "bring calls and chats to life" by sharing videos, images, and files while on a call or through instant messaging; there are also some location-sharing features as well to help you find people you may be communicating with. Lastly, "contacts presence" will add some status alerts for your phone book, letting you see if your contacts are available, busy, away, or unavailable, much like how Android integrates Google Talk statuses into its People app.

Unfortunately, it might take a while for the service to gain traction — it's only available for MetroPCS subscribers who are using the Samsung Galaxy Attain 4G, though the carrier plans to roll out additional RCS-compatible devices in the coming months. While it may only be minimally useful now, the service could be a differentiator for T-Mobile after its proposed merger is complete.