As I stated, it was a Verizon S5 that prompted me to get the phone (so, lucky you). It must be isolated to Sprint, because I have plenty of company with this problem as seen in a similar thread in Community message boards on Sprint.com (thread may be viewed at
https://community.sprint.com/baw/thread/167386). Copying/pasting the feedback from Sprint Customer Care. If you click on that link, you'll see plenty of other folks that experienced similar frustration.
SprintCare replied
Great to hear you are taking an interest in the Samsung Galaxy S5. Unfortunately at this time, you are correct, it does not support simultaneous voice and data (SVD) service. I can check your location to verify if and when you should be getting Spark upgrades. What is your zip code and nearest cross streets? Also, the fact that the phone is losing LTE, and your S3 worked on LTE fine in the same location, indicates there is a problem either with the phone or going on in the area. Once you provide your location, we can determine if this is temporary or more of an issue with the phone. Keep us posted, we are eager to assist you. - JonelleSprint Social Care
SprintCare replied
Sprint is investigating the issue with Spark model phones that seem to have trouble recovering signal when switching from LTE to 3G or vice versa. Right now, the best workaround, though temporary, is to turn the phone to CDMA. This should stabilize the signal for calls and data. I know you purchased an LTE phone and that you want to use it to its fullest capability. Please know that we are working to resolve this issue as soon as possible, so that you can begin to use that great device to its fullest potential. As soon as there is a fix, we will post It on the community device forums pages with all the necessary details - RobertSprint Social Care
SprintCare replied
We are working to find a resolution for this issue. It's only the Spark capable phones at this time, that do not have simultaneous voice and data (SVD) services. When we release any new details or updates, you can visit: newsroom.sprint.com for all information. - JonelleSprint Social Care
SprintCare replied
We do not intentionally leave information out when someone is purchasing a particular phone. If you ask for a certain model phone, we provide you with what you ask for. We also provide all details in our Sprint Forums, Sprint.com and Sprint Newsroom, to make sure that all of these details are available to everyone. Most dual-antenna EV-DO devices will support SVDO through the use of a separate transmitter and receiver for the active 1X voice and EV-DO data traffic. All of the Spark capable phones only have one antenna. Since this is happening, and you even know someone that this happened to, I will report this situation for you. If you have any other questions or concerns, let us know. - Jonelle Sprint Social Care
It is not the phone, it is Spark.
Also, there are probably a lot of apps on the phone gobbling up bandwidth that need to be uninstalled.
Amazon Suites is a bandwidth hog.
I have Verizon, so you really need some Sprint users to help you out.