If you cannot send or receive text messages on the iPhone 6, then this is usually due to an incorrect configuration of the message center. This means that the number of the message center must be adapted to your mobile carrier on your iPhone 6.
Unfortunately, there is on the iPhone 6 no setup menu, which is why it must be done with a netcode. We tell you here how to change the phone number of the message center.
On your iPhone 6 type via the keypad of the phone app the following code:
• *# 5005*7672#
Confirms the code by pressing the green phone icon.
Now checks whether the displayed number matches one of the following mobile operators:
• T-Mobile: +12063130004.
• AT&T: +13123149810
• Sprint: +17044100000
• Verizon: +316540951000
If the number does not match to your mobile carrier, then you have to change it. It works like this:
Type instead of "NUMBER", the number of your mobile carrier message center. You can extract the message center number from the list above.
Confirm the entry again by pressing the green handset. Finished! You should now send and receive text messages without any problems on the iPhone 6.