When I went into my local AT&T store, they said you only get the $25 discount if you are on NEXT. Basically, you get the $25 discount because they have you under 'contract' with the devices. What I was told was that even if I purchase the phone outright or BYOD, I won't get the discount. Were they mistaken?
I'm pretty sure the rep gave you the wrong info. In my account information, it describes the mobile share plan and has terms and conditions and a footnote describing the $25/month discount for "no annual service contracts" that reads as follows:
"For smartphones, discounted access charges apply w/ no annual service contract options (AT&T NextSM, bring your own, pay full price, or month-to-month)."
"5No annual service contract includes smartphones purchased with an AT&T Next installment agreement, purchased at full retail price, phones where you have completed your AT&T annual service contract term, or if you bring your own device to AT&T."
I should also mention that there is a discount for data buckets less than 10GB, but it is only $15/mo. (a reduction from $40 to $25). I received an odd benefit early in the year where they reduced the monthly cost of my phone to $15/mo. when we upgraded to this program with 10GB even though I was still on-contract. I think that was a one-time only promotion, however. Good luck.