Can Sprint phones do simultaneous voice and data (SVD) when used unlocked on a GSM carrier?

[AC Question]

Hi. I'm on T-Mobile and looking to get a used S7. The cheapest ones seem to be Sprint versions, but I know Sprint doesn't do SVD due to CDMA/LTE issues... or something. If I'm using an unlocked Sprint phone on T-Mobile, will it be capable of SVD on a GSM network.

Thanks

 

[Solandri]

From what I can piece together, the limitation is due to Sprint using 3 LTE bands simultaneously. Nothing to do with the phone (other than the phone not allowing use of the CDMA voice radio while using 3 LTE bands simultaneously).

GSM phones originally avoided this problem because they had a TDMA radio for voice, and a separate wideband CDMA radio for 3G data. Sprint and Verizon couldn't because they used the same CDMA radio for both voice and data (i.e. CDMA was actually the better, more flexible tech). LTE mostly uses OFDMA so came with its own radio and solved the problem for Sprint and Verzion (provided the data was over LTE). However, the move to multiple simultaneous LTE bands and limitations in the number of simultaneous radios allowed by the phone can cause the issue to resurface.

Older Sprint phones which don't support their LTE service on bands 25 and 26 (not on 41 as in the tri-band phones) are still able to do SVD.