Can no longer NumberSync after replacing sim

I'm not sure whether this should be in at&t or Priv section, but I'll post anyway and hopefully someone can help
I replaced my at&t Priv STV100-1 after I got it wet with unlocked STV100-2 last year. from the time I have had my Gear S3 Frontier I have always used NumberSync just fine, with the original Priv and with the replacement. Two weeks ago I noticed constant SIM disconnects, leaving me with a phone that worked 90% of the time and the other 10% there would be 0 bars and a message saying there was no SIM. Apparently replacing the sim fixed the disconnect issues, but I did not notice that NumberSync stopped working.
So today I noticed it stopped working because I forgot my phone at home but I did not get any calls on my watch. In trying to get it to work I had to disconnect NumberSync from the watch and set it up from scratch. I went thru the setup on the watch and I'm able to get the 5 digit code, but after logging into my at&t account it gives me error "Oh darn! We can't enable device syncing on this phone. Want to find out more? Call us at 800.331.0500 so we can help.
(MSSITWINREL12)"
Tech Support had a good reason, they said that the phone's SIM was changed, and the STV100-2 did not have HD Voice activated, which is required for NumberSync. I got frustrated with them because they said they could not enable HD Voice on my unlocked Priv STV100-2. So I'm totally lost. How can a device go from supported list to not supported? Could the problem be that I have STV100-2? Is it because it's unlocked? I'm totally lost.
Meanwhile I have the original semi-working STV100-1, very hard to read, but I'm thinking of putting the SIM in it and calling at&t to turn on HD Voice.
Anyone with suggestions please help. Keep in mind that I have tried the KeyOne and I'm not interested in it or the Key2/LE. I'm one of the few that REALLY like my Priv and its form-factor, among other reasons, and have 0 interest in a touchscreen-only phone. But again any suggestion is welcome.
Thanks. BTW this forum has never failed me, not in the whole 15yrs I've been here!

Originally Posted by cleveland216

I'm not sure whether this should be in at&t or Priv section, but I'll post anyway and hopefully someone can help
I replaced my at&t Priv STV100-1 after I got it wet with unlocked STV100-2 last year. from the time I have had my Gear S3 Frontier I have always used NumberSync just fine, with the original Priv and with the replacement. Two weeks ago I noticed constant SIM disconnects, leaving me with a phone that worked 90% of the time and the other 10% there would be 0 bars and a message saying there was no SIM. Apparently replacing the sim fixed the disconnect issues, but I did not notice that NumberSync stopped working.
So today I noticed it stopped working because I forgot my phone at home but I did not get any calls on my watch. In trying to get it to work I had to disconnect NumberSync from the watch and set it up from scratch. I went thru the setup on the watch and I'm able to get the 5 digit code, but after logging into my at&t account it gives me error "Oh darn! We can't enable device syncing on this phone. Want to find out more? Call us at 800.331.0500 so we can help.
(MSSITWINREL12)"
Tech Support had a good reason, they said that the phone's SIM was changed, and the STV100-2 did not have HD Voice activated, which is required for NumberSync. I got frustrated with them because they said they could not enable HD Voice on my unlocked Priv STV100-2. So I'm totally lost. How can a device go from supported list to not supported? Could the problem be that I have STV100-2? Is it because it's unlocked? I'm totally lost.
Meanwhile I have the original semi-working STV100-1, very hard to read, but I'm thinking of putting the SIM in it and calling at&t to turn on HD Voice.
Anyone with suggestions please help. Keep in mind that I have tried the KeyOne and I'm not interested in it or the Key2/LE. I'm one of the few that REALLY like my Priv and its form-factor, among other reasons, and have 0 interest in a touchscreen-only phone. But again any suggestion is welcome.
Thanks. BTW this forum has never failed me, not in the whole 15yrs I've been here!

Your previous device sounds like it’s the AT&T branded PRIV and your new device sounds like a factory unlocked PRIV instead. The problem is simply with AT&T only supporting enhanced calling features on carrier sold devices.

For HDVoice or VoLTE, the replacement will have to be a carrier supported device such as the AT&T PRIV or AT&T KEYone if you want PKB feature and VoLTE supported. Also, special note, AT&T does not support WFC on even the AT&T KEYone and I don’t suspect this will change.