SVDO is a simulateous 1x and DO call supported by two different transmitters. The 2nd data modem supports both DO and LTE.
VZW does not send their voice over DO (yet) so you need 1x for voice.
I don't know what either one of you is talking about. That was so far over my head, I hurt my neck looking up at it. My phone works and that's all I need to know. I'm glad I can talk and get data at the same time on 3G and don't have to worry about being in a 4G area for it...oh wait, I've never felt the need for data and talking at the same time, but at least I know I can do it. I can barely chew gum and walk at the same time. Just kidding y'all. My Tbolt rocks.
Actually I am correct.
1x voice, which is what VZW uses now, is a different technology from DO(or 3G as you refer to it). Given they are different technologies they cannot operate simultaneously as a single transmitter on a single RF channel. You cannot run them simultaneously on the same frequency (and have them work)...period. 1x advanced (not in TBolt) and new paging channels won't solve this RF interference problem either.
Thus to run simultaneous 1x and DO, you need two radios operating on different channels/frequencies. Voice and data are on two different independent connections.
The new radio you reference might be doing something interesting with voice and data, but that's not SVDO as supported in the Thunderbolt.
You don't have to believe me. Google around, find a tear down report, or look at FCC reports to find the same info.
you don't have to have the 4G LTE enabled to do simultaneous voice and data. The New 3G that is in the 4G towers are backwards compatible to other 3G devices such as my DX. The New 3G however is able to do simultaneous 3G Voice / Data on so equipped phones. And currently the TBOLT is the only to do SIMUL Voice Data over 3G. that is why att had to change their advertisements to say they have the only network where you can do voice and data on your IPHONE (changed from just PHONE).