My name is ***** ***** certified professional with over 10 years experience. I will be glad to assist you with this.
I am sorry to hear that you are having this issue.
Unfortunately the iPhone 6 sim card is not compatible with the iPhone 4, the iPhone 4 and 4s use the bigger micro-SIM chip which will not work with the newer phones that use the smaller nano-SIM chips. But your carrier can help you swap out that micro-SIM chip for the smaller nano-SIM, most cellular providers will get that to you for free.
Please reply and let me know if you need any other assistance or if everything is good, take a moment to rate my service by choosing one of the stars at the top, then click submit.
Thank you very much!
okay, no problem, they are both the nano sim so it should work.
Are both iPhones from the same cellular provider?
okay, did you reset network settings> Please follow these steps>
Step 1:Tap Settings.
Step 2:Tap General.
Step 3:Scroll down to the bottom of the page and tap Reset.
Step 4:Tap Reset Network Settings.
Step 5:You will get a prompt warning you that this option will delete all network settings and return them to factory default settings. Tap Reset to continue.
Step 6:Wait while your iPhone resets its network settings.
Once the reset process is done, your network settings will return to its factory default settings. Your iPhone will also automatically restart. Then check.
sounds good, let me know how it goes please.
okay, did you Insert the SIM card into the SIM card tray with the Tmobile logo and SIM card number on top (gold contacts facing down).
okay, unfortunately this sounds like the sim card has failed.
Okay, that is strange. A factory reset is the only other option to try.
Please follow these steps,
Did that work for you?
sounds good, let me know if you need anything.