With the iPhone already being on AT&T and Verizon, half of the major carriers in the US have the most popular phone in US. For years, there have been rumors of the next-generation iPhone coming to T-Mobile and Sprint in the next couple of years. With the next iPhone coming in the next month or so, rumors have surfaced that the next generation iPhone will make its way to the last two major carriers.

While T-Mobile will most likely merge with AT&T in the coming years, it won’t stop from current T-Mobile customers from purchasing the iPhone. While you can get an unlocked iPhone right now for the T-Mobile, it is not compatible with the networks 3G bands and thus can only run on edge data.

The T-Mobile rumor comes from Mactrast. The report says that the next iPhone will be making its way to all of the major carriers.

“The informant, who requested to remain anonymous, went on to claim that the iPhone 5 would also operate at 3G speeds on T-Mobile US network. Current unlocked iPhone 4 units can only operate at at 2G “edge” speeds on T-Mobile’s network, and lack certain network-dependent features, such as Visual Voicemail.

Further elaborating on the matter, the informant suggested that T-Mobile USA expects the iPhone 5 to launch sometime in early to mid October, which corresponds nicely with current speculation. He also expects the iPhone 5 to make a significant financial difference to T-Mobile. Our source was quoted as saying the following:

“We expect the addition of the iPhone, and the iPhone 5′s ability to run on our 3G network to make a significant financial difference for T-Mobile.”

With Apple wanting to completely take over the smart phone industry with its lawsuit with Samsung and expanding the number of networks the phone is on, it is likely that we see the next iPhone coming onto many more carriers.

Another network that is getting the iPhone is Sprint. The big yellow network was the first in America to gain 4G access in America and if Apple is interested in incorporating 4G into the next iPhone, then Sprint would be logical to gain the next iPhone.

From iDB:

According to the report, the device won’t be available to Sprint customers until mid-October. And since the iPhone 5 has been slated to launch October 7th, it sounds like Sprint might be late to the party. But better late than never I always say.

The news isn’t that surprising, given the recent reports floating around that the iPhone 5 will support both GSM and CDMA networks. Why wouldn’t Apple want a shot at Sprint’s 50 million+ subscribers?

With Sprint getting Apple’s smartphone this Fall, you have to assume T-Mobile won’t be far behind. And with the addition of two major carrier partners in the U.S., expect Apple to do big things this holiday season.

Are you excited to see the next iPhone on Sprint?