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Call Quality Between Mobile Networks

Bubbles121

ULTIMATE Member
I think this is a lesser talked about topic but I'd like to know other people's experiences. As I'm sure many of you know I'm a primarily Three user, albeit via Smarty. Three, Smarty, iD and Superdrug all use the same IMS service, as do Vodafone, Lebara, Asda and Voxi so these all come under their MNO in terms of call quality. I believe 1p, EE and (now dead) BT all share the same too. The only variation is O2. O2 it's self has decentish support for HD (AMR-WB) calling, even via 3G. However, the only MVNO it shares it's IMS services with is Tesco so Sky and Virgin run their own. Sky and Virgin do NOT support HD calling at all, for both 4G and 3G calls. Virgin don't even allow VoLTE by default, but I think that's because their IMS service is so dodgy they'd rather people who didn't know about it not use it.
These are the combos I know so far that work for HD (AMR-WB and EVS where possible, EVS is only host to host for the time being).
AMR-NB is a standard, old Non HD call.

AMR-WB is the first rendition of HD calling which works inter network. It offers good call quality (a huge step above NB) and much higher bitrates.

EVS (Stands for Evoluted Voice Services) only works for EE to EE calls, Three to Thee calls and Vodafone to Vodafone calls. It offers CD like audio quality and is the best you can get. These calls sound like the person is in the room with you - EVS calls require a supported device and network to function accordingly.

AMR-NB calls show a "phone" icon on Samsung devices next to the call time and nothing next to the call time on any other Google phone based devices.

AMR-WB calls show "HD" next to the time on Samsung and Google phone based devices.

EVS Calls show "HD+" next to the time on Samsung devices and Google Phone based devices show "HD" again next to the time (it doesn't differenciate between EVS and AMR-WB on Google phone based devices).
S20 Series and above support EVS, A series devices don't support.
iPhones don't differenciate at all between all of the 3 calling protocols but EVS IS supported from the iPhone 11/SE 2 and above.
Most Xiaomi devices support afaik as long as they have VoLTE. Nothing phone 1 also seems capable.

THREE
Three -> Three (EVS so CD like call quality)

Three -> Vodafone (AMR-WB - HD)

Vodafone -> Three (AMR-WB - HD - this has only been recently enabled so is a nice touch)

O2/Tesco/giffgaff -> Three (AMR-WB - HD, even when using 3G calling)

Three -> O2/Tesco/giffgaff (AMR-WB - HD, even when using 3G calling).

Three -> EE (AMR-WB - HD)

EE -> Three (NOT HD, AMR-NB)

EE (Including 1p, BT & Plusnet)
EE -> EE (EVS)

EE -> Three (NOT HD - AMR-NB)

Three -> EE (AMR-WB, HD)

Vodafone UK (including Lebara, TalkMobile and VOXI)
Vodafone -> Vodafone (EVS, recently enabled)

Vodafone -> Three (AMR-WB - HD)

Three -> Vodafone (AMR-WB - HD)

O2 -> Vodafone (AMR-WB - HD)

Vodafone -> O2 (AMR-WB - HD)

O2-UK (Including giffgaff and Tesco Mobile)
O2 & Tesco VoLTE -> O2 & Tesco VoLTE (EVS, recently enabled)

O2 -> Three (AMR-WB - HD)

Three -> O2 (AMR-WB - HD)

O2 -> Vodafone (AMR-WB - HD)

Vodafone -> O2 (AMR-WB - HD)



This is all that I am aware of so far, so people feel free to fill in gaps where I have missed (which is quite a lot lol)
 
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Whilst I cannot go into the detail of possible Mobile Audio Codecs that you have describe, I can say for many years I have been a Vodafone Business Customer for my day to day Comms and have over the years noticed that Voda to Voda (Business to Business) Calls are always of extremely high Audio Quality, next in line is Voda Contract Customers and the worst quality has always been when calling PAYG Customers, I've noticed this over the years on both 2, 3 and 4G.

Im also a long term Direct Consumer Customer on EE (Ex T Mob and Orange Take Over Customer) and although not on Business use, EE to EE Voice Calls have always been more impressive than calling to other Networks.
 
Whilst I cannot go into the detail of possible Mobile Audio Codecs that you have describe, I can say for many years I have been a Vodafone Business Customer for my day to day Comms and have over the years noticed that Voda to Voda (Business to Business) Calls are always of extremely high Audio Quality, next in line is Voda Contract Customers and the worst quality has always been when calling PAYG Customers, I've noticed this over the years on both 2, 3 and 4G.

Im also a long term Direct Consumer Customer on EE (Ex T Mob and Orange Take Over Customer) and although not on Business use, EE to EE Voice Calls have always been more impressive than calling to other Networks.
I doubt it would be any different between all 3 tiers now with VoLTE in existence.

EE seem very limited on outgoing HD calls.
 
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Vodafone -> Vodafone (AMR-WB - HD)
I think Vodafone to Vodafone is EVS, was on a call today from my contract Vodafone SIM to other family member on Talkmobile the call quality was better than usually it was showing as HD+ on my phone.
 
I think Vodafone to Vodafone is EVS, was on a call today from my contract Vodafone SIM to other family member on Talkmobile the call quality was better than usually it was showing as HD+ on my phone.
HD+ is indeed EVS, thanks for spotting this. I'll add it now, nice to see Vodafone adding support for it as it didn't have it last time I checked.
 
HD+ is indeed EVS, thanks for spotting this. I'll add it now, nice to see Vodafone adding support for it as it didn't have it last time I checked.
Might only be Vodafone and mnvo owned by Vodafone Talkmobile Voxi calling my parents phone on Lebara same phone as mine was only HD.

The call I had HD+ was between Vodafone and Talkmobile own by Vodafone.
 
Might only be Vodafone and mnvo owned by Vodafone Talkmobile Voxi calling my parents phone on Lebara same phone as mine was only HD.

The call I had HD+ was between Vodafone and Talkmobile own by Vodafone.
It'll be device dependant. Lebara also uses the same IMS so no doubt it will support EVS too. Samsung A line phones don't do EVS and neither do phones older than the iPhone 11. (Seems to be iPhone 8 and up for EE).
 
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I got Samsung A series phone, the phone that had HD+ was my A52s 5G.
This seems a lot more variable than I thought. Didn't think the A line was capable of EVS, but I've only tried Three's EVS. Nothing phone 1 <-> S21 = EVS, A20e/A12/A71 <-> Nothing phone 1 = No EVS, at least on Three.
 
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I was on a Scottish island recently and received a call while connected to Vodafone 2G (with the signal meter showing "G", not even "E"). I hadn't realised how much things had improved in voice call quality over the years until I struggled through that call!
There's a GPRS O2 mast near me... My friend is on Tesco and she was speaking on the phone via O2 G...... my god, it was basically unintelligible - or maybe I've gotten too used to my EVS ;)
 
I think this is a lesser talked about topic but I'd like to know other people's experiences.

Inbound VoLTE HD Voice calling to Three from other networks is completely broken.

The situation can be summarised as follows (if HD Voice supported by the handset and in 4G coverage):

Vodafone and EE - All calls fine in HD between the two.

Three - Can call 3, Voda and EE in HD but can only receive HD calls from 3 numbers.

I've not included O2 in the list as VoLTE on that network seems generally broken in multiple ways.

So basically you need to be on Vodafone or EE if you want to make and receive HD calls with the vast majority of UK mobile phones that are capable of making them. Three is only suitable for people that make calls but don't receive them.


EDIT: Before anyone mentions it, yes there are subtle codec differences for on-net HD and MVNOs as mentioned often fail to provide HD or sometimes even VoLTE! Also 3G transcoder free operation should be universal, but is also obsolete. The above is just a simple summary.
 
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