crushingyen, Jul 23, 2014 : NOTE: Not everyone will be undergoing problems when using their OPO on T-Mobile out-of-the-box, but for those who are, this should solve the issues you are facing. I've seen quite a few people who have troubles with getting their devices working on their respective GSM carriers. Knowing a friend who has the OPO and made the switch from his prior device (HTC One M8), he was undergoing problems with getting his device up and running and we at some point found the appropriate solution to get full service (LTE and everything). So with that said, below are the steps on how to seamlessly transition to the OPO on T-Mobile USA. A. Tutorial: 1a. Use your existing Micro SIM card to activate your OnePlus One (existing T-Mobile customers): This is the preferred method because the SIM card is already working on a previous provisioned T-Mobile phone. If you activate a new SIM card in your OnePlus One, the network will not recognize the device as its IMEI number cannot be cross matched with the device name in T-Mobile's database. As a result, you will get notifications on your phone asking you to "Sign into T-Mobile Network", because your phone isn't "provisioned" to use their data plan. If your prior device does not use a Micro SIM card, you will need either a SIM Card Cutter, or a SIM Card Adapter (http://goo.gl/PFdDNE). The adapters are just as expensive as the cutter + adapter combo, so there's no reason to pay just as much for the adapters alone. 1b. Getting a new SIM card and activating it in a T-Mobile branded device (new customers switching to T-Mobile): If for some reason you obtained a new Micro SIM card from T-Mobile, you will need to make sure to activate it on an existing device that is provisioned to work on the network before placing the SIM card into your OnePlus One. Easiest method is to go into the T-Mobile store and just get the SIM card activated beforehand. 2. Updating the T-Mobile APN: When you first get your network up and running, it will not come out of the box with the APN settings optimized for the T-Mobile network. In order to change the APN settings, do the following: Open Settings Tap on Mobile Networks Tap on Access Point Names To get the best results, I would recommend updating the T-Mobile US LTE APN with the APN settings below, as they came from the pre-set configurations for the latest flagships i.e. HTC One M8: Name: T-Mobile US LTE APN: fast.t-mobile.com Proxy: Not set Port: Not set Username: Not set Password: Not set Server: Not set MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc MMS proxy: Not set MMS port: Not set MCC: 310 MNC: 260 Authentication type: Not set APN type: default,supl,mms,hipri,dun APN protocol: IPv4/IPv6 APN roaming protocol: IPv4 APN enable/disable: APN enabled Bearer: Unspecified MVNO type: None MVNO value: Not set After that, you should be fully up and running on the T-Mobile network with all the network bands available. If there are any other issues, let me know and I'll try my best to clarify the steps. B. Frequently Asked Questions (FAQ): Q1. The OPO isn't showing LTE on my phone - it's only showing 4G. What gives? A1. Your phone is getting LTE signals, it's just that CyanogenMod 11S represents these signals differently. A breakdown of the signal interpretations is shown below: 4G on the OnePlus One = LTE in the Settings app = LTE on T-Mobile H+ on the OnePlus One = HSPA+ in the Settings app = 4G @ 42 Mbps on T-Mobile H on the OnePlus One = HSPA in the Settings app = 4G @ 21 Mbps on T-Mobile 3G on the OnePlus One = 3G in the Settings app = 3G on T-Mobile E on the OnePlus One = EDGE in the Settings app = EDGE on T-Mobile G on the OnePlus One = GPRS in the Settings app = GPRS on T-Mobile Note: The answer to this question was specific to those on the 25R build of CyanogenMod 11S. Those who have updated to the 30O OTA build should have LTE in your status bar instead of 4G. Q2. I put my SIM card (old/new) into my phone and it works just fine. What's the point of this tutorial? A2. Like I noted before, this tutorial is meant for people who have had problems with getting their phone up and running and are looking for a solution. If it works for you out-of-the-box, good for you . Q3. I noticed that there were extra APN types like 'hipri' and 'dun'. What are these for? A3. The two extra APN types are defined as the following: hipri: This setting ensures that when your phone connects to the network, it uses our recently modified APN as the first APN of choice dun: This is for those who are looking to tether on the T-Mobile network. Adding this will let the phone know which APN to use when users are attempting to tether with their phone Q4. Where can I find certain information like my IMEI number? A4. On your phone, go to Settings --> About Phone --> Status. Q5. Help! I'm not receiving text messages on my phone after applying these settings! What do I do? A5. You may have a CM 11S feature enabled called Voice+. This feature is used to have all your messaging apps by default use your Google Voice number to handle the outgoing text messages from your phone. If you do not have a Google Voice number, then you'll need to do the following to get text messages working with your original number: Check and make sure that Voice+ is disabled: Settings --> More... --> Voice+ (credits to @WJenness for the solution) Q6. I'm not receiving any group MMS downloads in my group chats in the Hangouts app. How do I get this to work? A6. I've just updated the tutorial to include APN changes for those who use Hangouts as their default SMS app. Look above for the recent changes. Q7. After the 30O OTA update, I'm no longer able to store MMS messages. Is there something wrong with these settings? A7. There is nothing wrong with your settings. People who have updated their phone have had numerous reports of this issue; make sure to clear the data from your desired MMS app and relaunch it again.