Sprint VoLTE Discussion Thread Redux

[Member21]

If you have a new phone that supports Sprint VoLTE and you call a landline phone, does the call go over the regular old CDMA or does it initiate over LTE and then go into the landline network?  

[RAvirani]

3 hours ago, Member21 said:

If you have a new phone that supports Sprint VoLTE and you call a landline phone, does the call go over the regular old CDMA or does it initiate over LTE and then go into the landline network?  

The call goes over the LTE RAN and it is routed to the landline network. 

[iansltx]

Just called a friend on VZW. Decided to call him rather than the reverse based on y'all saying the probability of HD voice was higher.

HD voice worked. There's a definite difference between HD and HD+ of course, but I'll take the quality increase over a standard mobile call any day of the week.

[ingenium]

Just called a friend on VZW. Decided to call him rather than the reverse based on y'all saying the probability of HD voice was higher.
HD voice worked. There's a definite difference between HD and HD+ of course, but I'll take the quality increase over a standard mobile call any day of the week.

What is HD+?

In my experience, when I'm on calls with Verizon users it uses EVS for the codec. I may have seen EVS-WB once with a Verizon call too. Calls to att customers used a lower tier codec, AMR-WB. I don't call other Sprint users very often, but I think it's usually EVS if they're on VoLTE or Vowifi. VoLTE/vowifi calls that go through POTS use regular AMR.

Sent from my Pixel 4 XL using Tapatalk

[iansltx]

2 hours ago, ingenium said:

What is HD+?

In my experience, when I'm on calls with Verizon users it uses EVS for the codec. I may have seen EVS-WB once with a Verizon call too. Calls to att customers used a lower tier codec, AMR-WB. I don't call other Sprint users very often, but I think it's usually EVS if they're on VoLTE or Vowifi. VoLTE/vowifi calls that go through POTS use regular AMR.

Sent from my Pixel 4 XL using Tapatalk
 

I didn't check codecs this time. I'll see if I can check this evening on a Sprint-to-Sprint call (VoLTE all the way across, S20 to S20).

HD vs. HD+ shows different logos on my phone. Apparently no one I call on AT&T uses a new enough phone to have the newer codecs.

EDIT: Inbound from VZW uses 12.2 kbps AMR-NB. Outbound to VZW uses 12.65 kbps AMR-WB and shows up as HD. This was using VoLTE on my side.

EDIT 2: Sprint-Sprint was EVS at 13.2 kbps. I should be less surprised of the quality increase for a negligible bandwidth increase, but here we are.

[iansltx]

Just did an AMR-WB 12.5 kbps (pretty sure those were the numbers) call where a T-Mobile customer called me. Not sure whether it was WiFi or VoLTE, as I had him turn off WiFi partway through and the call didn't drop, but while the call wasn't quite as clear as EVS (or at least didn't feel quite as clear) or Duo, it was perfectly listenable, despite running in an area I know is iffy signal-wise.