Report: iPhone update authorizing T-Mobile’s LTE network arrives Friday

Last week I wrote a post attempting to answer all of the lingering questions about whether current-generation iPhones would work on T-Mobile’s networks. There was only one answer I couldn’t get out of Apple(s aapl), and that was when it would send out the iOS update officially activating support for T-Mobile’s brand new 4G network. Well, Apple remains mum, but TMoNews seems to have gotten the answer: April 5.

An internal T-Mobile screenshot leaked to TMoNews states that the iOS update will not only authorize the T-Mobile network (T-Mo’s 2G and a portion of its HSPA+ networks are already supported), but will enable Apple’s visual voicemail and MMS features on the carrier as well. Here’s the text of document:

“The T-Mobile Carrier Update is a minor iOS software update that enables official iPhone support by T-Mobile. When installed, the software update enables a handful of capabilities like Visual Voicemail, MMS Settings and Network/Device optimizations that customers do not have access to today. On April 5, the software update will begin being pushed via OTA to all iPhone devices on the T-Mobile network with iOS 6.1.x or higher.”

I asked Apple and was told it isn’t commenting on a rumor, so I suppose we’ll have to wait until Friday to see if an iOS update shows up in iTunes.

Keep in mind that only the North American GSM iPhone 5 model will work on T-Mobile’s LTE systems, which are now live in seven markets, and to connect to T-Mo you must have an unlocked device. All generations of iPhones will work in T-Mobile’s 2G footprint and on its HSPA+ networks in about 50 markets today. The carrier is expanding that HSPA+ support quickly as it undergoes a major network overhaul.