Thanks to Albert C. Lee for initial information on this topic.
Since your phone is digital, it uses a codec to determine how the voice data is compressed to digital. 13k (Qualcomm's Purevoice) is the highest voice rate there is. EVRC (Enhanced Variable Rate Codec) benefits the carriers because it uses a reduced rate, which means less bits to stream, more calls to go around. EVRC is supposed to sound as good as 13k, but most haven't experienced this to be true.
Note that not every area supports EVRC. Your phone actually drops to analog, or the old 8k Codec as soon as you make a call if you are using EVRC in a non-EVRC area.
The quick way to access this setting without even having to enable testmode menus is done by entering:
V O C O D E <FCN> <FCN>
This will give you the options of 13k, EVRC, or Home/EVRC Roam/13k.
If you use the Test Menu to change the Vocode option, you will have the additional choice of 8k.
In most areas, 13K is the standard codec. If you switch your phone to use EVRC, you will notice that this will only affect outgoing calls. The originator of the call controls which codec is used, and as such, if the network you are using is still officially 13K, that is what your phone will use when a call is received from the network.
Apparently however, Bell Mobility in eastern Canada has switched their network to default to EVRC now, and all incoming calls will be EVRC. They have also forced all calls to EVRC now. Even if you have your phone set for 13K, the network will still setup the call in EVRC. (Thanks Frank)
September 25, 2001: Telus Beginning to force EVRC in BC?
Some interesting stuff happened one day last week. Bell is forcing EVRC back east, and many US providers are forcing EVRC to save bandwidth too... Maybe we are beginning to see the first of this here in BC:
This is with my StarTAC 7868W. Last Wednesday (the 19th of September) I was in North Surrey, near 100 Av., and 120 St. I made approximately three 5 minute calls and I noticed a distinct difference in the sound - so I checked with test mode, and sure enough, the calls were being forced to '8EV' - EVRC. This was on Cellular Channel 384. I checked my vocoder setting, and it was set to 13K.
I changed set the phone to my second NAM, which prefers the ClearNET SID 17500 on P450, and it would use 13K. Switched it back to my first NAM on C384, and it would use EVRC.
I also have a StarTAC 7860W, and it was also on C384, so I made a test call with it in the same area, and it used 13K... Strange I thought.. I completely turned off my 7868W, pulled out the battery even, and powered it back up - and then it would make a 13K call... So either my phone had a moment where its internal settings got messed up for vocoder setting, but I doubt it.
Maybe Telus is 'testing' EVRC on phones with a higher usage for testing in various areas, and maybe they had ran the test in that area at that time thinking no one would notice...
The ringing sound when calling someone sounds quite different on EVRC, so it makes it easy to tell even without the status screen from test mode on the StarTAC.
Anyone else experienced this? Or at least 'keep your ears peeled' for more of this happening... I for one like 13K :)
October 1, 2001: Forced EVRC on Telus now live in BC
Well, as a follow-up to my previous post last week about seeing calls using EVRC, it appears that as of today, all calls from both of my phones are now using EVRC, no matter what I set the vocoder to, or whether they are incoming or outgoing calls.
I noticed it on a call around noon today while in Richmond (Mon Oct 01), and throughout the day it was also only using EVRC in South Vancouver, Burnaby, Coquitlam, North Surrey, and Langley.
In Richmond, around 12:30, I even saw what I think was the actual switch-over. One of my phones is a StarTAC 7868W, which switched from C384 to P350, and the other, a StarTAC 7860W Dropped to Analog for about 3 minutes. Turning off the phone and turning it on wound find no digital signal in Richmond :) Could this have been them turning off the Digital network on the cellular side while they 'turned on' the EVRC equipment? I think it was too much of a coincidence.
Even as I type this (~7:20 PM) Both phones still use EVRC. /Sometimes/ the phones will use 13K for one call after first being powered up, but then its all EVRC from there.
On the other hand: My StarTAC 7868W, when logged onto P450 (the old ClearNET network) will ONLY use 13K. If I set it to EVRC, or the old 8Kb codec, it will always use 13K. Kind of strange?
I also have confirmed its not 'just me' - I checked with someone with a StarTAC 7760 in Maple Ridge - first call after powerup was 13K, but after that they were all EVRC.
What do you think guys? I hope the capacity gains are worth the switch. EVRC
sounds a lot scratchier to me. 'S' & 'T' sounds are a little painful to listen
to now - but that might just be me. :)
October 2, 2001: Telus Mobility Keeps 13K vocoder on their Service Lines
There has been some discussion on the newsgroups, at it appears that Telus Mobility has programmed their mobile switches to use the better vocoder when dialing into their customer service line, *611.
I've been testing this a bit. It also looks like Telus Mobility has also set the other numbers that reach customer service to use 13V as well.
All of these BC customer service numbers seem to always use 13V:
611 *611 *711 811 *811 604-291-2355 1-800-661-2355
No way I'm testing 911, but if someone DOES need to use it, let us know :)
But 310-2233, and their Alberta CS# 1-800-661-3681 do not.
Makes for a good comparison of the codecs, for instance call one of each and you can REALLY hear how much EVRC butchers the 'Telus Chimes' at the beginning.
Talk about sly - The definition is most appropriate:
"in a manner intended to avoid notice"
Ryan Goolevitch - ryang@trideja.com
Last Modified
October 2, 2001