same message after unlock phone not allowed #mm6

We are here to help with the #mm6 error message you are getting @pelon1z.

When you unlock your phone, switch the SIM card, and make a call. If your device is tethered to another carrier. You will get the error “Phone Not Allowed: MM#6 Error.” This error means that you are trying to use a phone tethered to another carrier.

Please answer the following questions so we can provide further assistance:

• Are you trying to use a device you purchased from a third party seller on the AT&T network? The device may not be unlocked from the previous carrier.
• Is the device an AT&T device and you are trying to use it on another carrier? You will need to submit a Device Unlock Request. 
  • Please note that you must meet the Unlock Eligibility Requirements.

We look forward to hearing from you!

Samantha, AT&T Community Specialist

Samantha - I'm having the exact same error on a Samsung Galaxy S7 bought at AT&T that AT&T has given me the unlock code for, I entered it, and it said the unlock was successful. But I'm still getting the error "phone not allowed #mm6" when I try the phone with other GMA carriers. 

Just because the phone is unlocked, does not mean it will work with any other service provider. You need to check with your new provider and find out if your particular phone is eligible to work on their service. By the way phone not allowed is not the message you get if the phone is locked. Is the message you get if the phone is not compatible.

Thanks. The phone is compatible when I check the device (Samsung Galaxy S7) and the network (GSM not CDMA) but when I check the specific IMEI it says it's not compatible on any other provider other than AT&T. It appears AT&T has "marked" the IMEI such that I cannot use the phone anywhere else

@dhneedham  I don't know what you mean by "marked for AT&T "? 

   And you didn't say what service provider you were trying to use? 

   Unless there was fraud or non payment involved there's no reason the phone could not be unlocked to work with another service provider. AT&T doesn't usually blacklist for non-payment, they will for fraud.  But in either case, it would prevent the phone from working on any service provider and it would say blocked from Network.

When you unlock your phone, switch the SIM card, and make a call. If your device is tethered to another carrier. You will get the error “Phone Not Allowed: MM#6 Error.” This errormeans that you are trying to use a phone tethered to another carrier.

This is the strangest statement I have ever seen and it does not make any sense because it seems contradictory. I understand the phone being incompatible with a different carrier. But if iPhone is unlocked, does that or does that not remove the software "tether" that keeps it from functioning on another service provider.

No amount of Googling has managed to come up with any other explanation other than unlocked phones can work on other compatible service providers. No such contradictory words such as unlocked but still tethered come up.

Okay I've entered that specific error mm6 into Google browser and come up with a informational post on refurbished phones and this particular error.

https://www.theandroidportal.com/how-to-fix-phone-not-allowed-mm6-error/

If you read the article it does refer to unlocked phones that are still Tethered to the original carrier.

The article does not dive into the issue of refurbished phones having incompatible replacement parts. 

I've checked the IMEI at many other service providers: AT&T, T-mobile, Metro, Sprint, Mint, Boost, Verizon, Cricket. It's only compatible at AT&T and Cricket, which AT&T acquired and runs on the same network. 

I'm having the same issue with an S6 active made exclusively for ATT...I got the unlock code from ATT put in Tmobile metro.pcs sim and MM#6 phone not allowed comes up....I think you have to update your network or access point to add the same one as the sim card your trying to use

Read the link I posted