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3000 posts

Uber Geek


Topic # 6113 28-Dec-2005 11:18
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Something which seems to be getting left in the wayside recently with techological advances is the quality of the speech, a phones primary function.

Some phones on 027 can have a thing called Voice CODEC changed, this makes the voice sound different, much like Voda3g's fantastic voice clarity, and in my opinion, better, not so muffled and much more natural than "i'm on a cellphone" sounding.

There is an alternative which was orginally the design spec for CDMA and is rarely used today.
The standard is 2-8k EVRC "Enhanced Variable Rate Codec"
the other option is 13k QCELP "Qualcomm Advanced Code Excited Linear Prediction"

EVRC is used purely for network cpacity and it has less packetloss blips (I like blips and squarks as I know when signal is fading)

Hyundai 310,610 TX21b, TX30, can be changed to "13k QCELP" instead of "EVRC" under voice option on the menu. The code for these is ##20022002 then press [red phone]

The Hyunday TX21b does have an issue with echo after changing so this one is best left alone, the Hyundai 310/610 have such patheticly low microphone gain they are barely usable as phones anyway so I wouldn't even bother though they benefit alot from the change

The TX95, TX115 Tx130c is also ##20022002 then press [red phone] but you need to enter the code which only Telecom can provide. after this DO NOT prees okay but wait, there will be a slew of options that show, one being "voice option", change this from "8k EVRC" to "13k Qcelp"

Samsung N361, N391 and probably all the older ones can also be changed but it's very deep in the setup programming menu so I cant reveal the codes. The Samsungs also really benefit from this for some reason, especially the built in answerphone. it's known as [evrc call], when found, scroll down and [13k call] will appear, then go the the finish.

It's a subtle change for most people and something you probably won't notice on the handset but the person at the other end will usually notice a dramatic change, your voice comes across louder and clearer, It also makes a difference in carkits, you will get a bit of background noise but speech is very clear and intelligable.

Nokias cannot be changed. (Chipset is not Qualcomm MSM series)
Sanyo's Cannot be changed. (locked up too far by operator, sprint is to blame, not t'com)
Pantech MIGHT be changeable (hyundai based)

To hear the differenc on the pc download PureVoice by Qualcomm

Purevoice is the better sounding QCELP one as detailed in this post,
Smartrate is the default EVRC, (lower quality)

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3000 posts

Uber Geek


Reply # 25387 28-Dec-2005 11:28
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I dare say this for fear of getting flames, It makes your phone sound more like Vodafone which also means when calling customers on the other side, calls are of much higher quality. the primary reason for me having to change it.

CODECS used in mobile networks if you want to do some reading.

CDMAONE r 1.0 comes standard with 13k QCELP (excellent)
CDMA1rxtt and beyond comes standard with a (unprecictable) variable EVRC codec. backwards compat with older better but lower network capacity 13 QCELP

GSM comes standard with (v Good) EFRGSM 6.10 Codec. 13k or 16k?
GSMUMTS comes standard with (Excellent) AMR Codec. VBR

Failures or old stuff long forgotten about.

GSM HR 7k, a half rate codec that sounded diabolical.
GSM FR 13k, just very old and artificial sounding by todays standards
CDMA QCELP 8k, reasonably good but suffered from a tinnyness.

GSM has some interesting security wrappers, apparently (correct me if i'm wrong) date rate is about 32k in a voice call

*edited.. i got GSM rates screwed up.

167 posts

Master Geek
+1 received by user: 2

  Reply # 25595 1-Jan-2006 23:27
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do you no why telecom doesnt use the better sounding audio codec as standered?
also do you no how to unlock this on the pantech tx-130

242 posts

Master Geek

  Reply # 25619 2-Jan-2006 22:13
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Cool, it does work on the Tx130c

I like cats... they taste like Chicken

3000 posts

Uber Geek


Reply # 25656 3-Jan-2006 14:49
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From some websites i'll quote, I did some more Googling after discovering this in the menu (and just noticed a vast difference) and it' seems to ring quite true. There is little saying "EVRC SOUNDS BETTER" and probably only on buzzy American accents at megaphone volumes.
EVRC works at 2-3k typically and adjusts itself up or down to compensate, I think this is it's main downfall and that noise suppression.

QCELP is also used for the "voice tones" over CDMA and the phones recording format.


Under the "Voice Option" menu you can also change your vocoder! 13K QCELP is a better-sounding vocoder, but many systems are forcing EVRC for spectrum considerations.

New technology called Enhanced Variable Rate Coder (EVRC) is included to support increased network capacity

In a best case scenario EVRC sounds pretty good but is kind of 'dead' sounding

SprintPCS S**ks!!! wrote:
> I thought everybody figured out the voice is just a special type of
> data.
No, actually, it isn't. Voice is VOICE... it can be companded into an
8kbps EVRC vocoder and come out reasonably well at the other end. 1xRTT
data on the other hand, can burst up to 144kbps... the equivalent of
*18* voice channels. Even if you base calculations on the older, better
sounding 13k QCELP vocoder.

The big problem with passive noise suppression (such as that implemented in the EVRC CODEC on CDMA) is that it cannot accurately remove noise without damaging the desired audio.

Nokia still has to perfect the sound reproduction with EVRC

End quote:

the Nokia one as a footnote, I can't agree more, the 6385 especially was horrible tot the poor peron at the other end. It sounded like someone was calling from the moon.

Pretty much sums is up, EVRC is the "standard now" but as I use the QCELP 13k on my private phone and EVRC on my "work" mobile (both samsung n391) i'm really noticing the difference when using them together., mainly being the stuttering over EVRC when people are talking and people asking me all the time what i said, especaily being asked to repeat numbers.

I have personally tested this on
Hyundai 310 (I have PILES of these things given to me) (have)
Hynudai 610 (smashed)
Hyundai tx21b (have)
Hyundai tx30b ("Gold" phone from WhareWare) (lost)
Hyundai Tx95c (in australia which worked awesome in the sticks) (sold)
Hyundai Tx115c (friend)
Samsung n391 (current phone)

If I could get some dealers to test this out for me on a wider scale, i'd be pleased to know any results, Good or bad!!!

21 posts


  Reply # 25666 3-Jan-2006 19:20
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I have a TX-95c and when i tried the ##20022002 + [red-phone] key it got me into NAM programming and not the voice options you're talking about (i guessed the lock code for the NAM programming).

but there is nothing about voice codecs or anything, it only has a menu which has 2 options


and in each is a sub menu containing

Phone Number
NAM Name

what are these options for??

and where else would i find the voice codec options??


3000 posts

Uber Geek


Reply # 25667 3-Jan-2006 19:28
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2 nams, Interesting in itself, nokia's have 5 by default, reduced to 1 by t'com.

You need to enter no codes or even touch the nams (advised against)

When you first press the ##20022002 [red phone] you should get a menu with "Nam program" among other options and keep scrolling and "voice option" should eventually appear

let me know what options you get after the "##20022002 [red phone]" too so I can update :-)

21 posts


  Reply # 25668 3-Jan-2006 19:37
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when i press #20022002 + [red phone] and then the lock code all i get is a little message pop up saying

"Welcome to NAM Programming"

then it goes to a menu

The menu structure looks like this:

1) NAM 1
|______ ESN
|______ Phone Number
|______ NAM Name

2) NAM 2
|______ ESN
|______ Phone Number
|______ NAM Name

they are the only 2 options, there is nothing else.

and when I leave the menu it says

"NAM Setup Ended"

and my phone restarts.

Note: when viewing this menu my phone goes offline and the little phone with the red-line through it (offline icon) appears on the screen at the top.

3000 posts

Uber Geek


  Reply # 25669 3-Jan-2006 19:55
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What happens if you don't enter in the "lock code" or "spc code"?

21 posts


  Reply # 25670 3-Jan-2006 19:58
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nothing, it just has the picture of a padlock (same as when accessing security menu from normal settings menu) and the box to enter the lock code into and has one option "Cancel" which is the right "soft-key".

If i don't enter anything it just goes back to main screen.

3000 posts

Uber Geek


  Reply # 25671 3-Jan-2006 20:05
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Hmmm. weird, I might be stumped on this one.

When you enter ##20022002 [RedPhoneKey]

It SHOULD come up with a menu with:

[Nam program]
+Ask SPC code
[Psid/Rsid lists] (or something like it)
+PRL etc etc
[Voice option]
+8k EVRC
[Something else i forget]

without asking for any codes,

21 posts


  Reply # 25672 3-Jan-2006 20:13
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nope, it just goes straight to asking for the spc code..

suks!! i wanted to change the vocoder lol

i also tried it on my mums TX-115c and it also goes straight to the spc code screen (her code is different to mine tho so can't get into it)

81 posts

Master Geek

  Reply # 25717 4-Jan-2006 18:10
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i have a tx95c, i will probably change it since you say its better, but can it be changed back?

81 posts

Master Geek

  Reply # 25718 4-Jan-2006 18:23
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ok weird. i put in ##20022002 and it made me put in my code. well my code in security is 1234, but that wasn't working. weird. i wanted a 6 didgit code. wtf?

574 posts

Ultimate Geek
+1 received by user: 8

  Reply # 25721 4-Jan-2006 20:46
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If it's asking 6 digits it's likely to be asking for the SPC (Service Programming Code).

The SPC isn't public knowledge and if you don't know what you're doing it's a good way to stop your phone from working. It's also against forum usage guidelines to post SPC codes.


Working for Service Plus -

Authorised Service Agent for Apple, BenQ, Sony, and Toshiba - warranty & non-warranty repairs.

81 posts

Master Geek

  Reply # 25724 4-Jan-2006 22:30
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ok, why is it a SPC on my phone?

and it seemed fairly simple from the posts on how to change it.
are you allowed PM the SPC Code?
or is there anyway i can find it out?


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