atcomsystems.ca/forum Forums VOIP Phones & IP PBX VoIP & Cloud Phones, Hosted PBX, General IP Phones G.711 vs. G.723

I have just switched our IP setup for our office from G.723 to G.711. I have seen several posts throughout this site about this and when Vodavi (our system and we sell them) announced today that their new software package defaults with G.711, I figured I would try it out to see what would happen.

What an amazing difference! Calls are MUCH more clear and consistent.

I know that 723 was (is) a protocol designed to conserve bandwidth through voice compression. I also know that 711 doesn't. Still, nowadays with everyone having cable or DSL at remote sites, I don't see the harm in reducing the compression to improve voice quality. I mean seriously, if the router is configured to prioritize voice packets, should it really make a difference except to improve voice? 768K+ with these connections should still allow plenty of room for a few IP phones or tie lines plus data.

Am I wrong here in my assumptions? So far, it seems like 711 (u-Law) works at toll-quality or better, while 723 was cell-quality at best.

I am considering changing our many customers who are using VoIP for ties or for remote users to 711 based upon our internal success. Before I do this, I would like to get a professional's opinion and that's the reason for my post here.

Any suggestions or advice will be greatly appreciated.

:shrug:

Even with cable or DSL at 1000K download speed, you need to look at the upload speed which is usually only 128-256K.

I've tried using 711 for tie & phones, works OK for 3-4 phones if there's hardly any data traffic. One customer had to get a second cable modem at each location just for voice traffic. Another customer can't use 711 for tie because lack of upload speed distorts DTMF too much for the voicemail.

711 works great for internal use, but I've still had the best luck with 729 if you need to go over the internet. Try it and see, but be ready to change back to 729 if or when they complain.

If you need help tweaking the settings, let me know. I've only worked with Toshiba, but most systems should have the same or similar settings.

Discamer: I'm not a VOIP expert, but I just happened to be taking an Online CTP course.

G.723 has the highest compression and transmits at 5.3 or 6.3kbps

G.729 is 8Kbps

G.711 is uncompress (PCM) at 64Kbps (although Toshiba says it uses 130Kbps per talk path)

I've had some complaints of words being cliped using 729 (and echo with POTS lines)
Toshiba, for example, says to always use G.711 unless you can not spare the bandwidth.

Don't forget that not only is there 64KBS required for voice but most switches require an additional section of bandwidth for packet headers. This can be an additional 16KBS or more.. Rule of thumb..at least 80KBS per call for true toll quality. If Toshiba does require 130KBS per talk path then that is indeed a hog. You can see where this would tax the resources of alot of DSL and cable connections unless they are running upgraded business class or better.

I use g.711 for everything. Softphones connected via DSL/cable, IP phones, and IP trunks. Works great.

G711 will use over 100k if you dont use silence suppression (only one person talks at any one time! so when you are listening you are transmitting silence to the person speaking?)

G711/G723/G729 are not protocols they are codecs.
G711 is the same codec used for ISDN, there is less compression than the others so you will get better quality!

The important thing to remember if the calls are going through the internet you really NEED QoS. As you have no control over what happens i.e. loss, delay and jitter.

Just finished the Online CTP from CPX Connect (Toshiba). Boy when they say fast track they aren't lying. Makes an old telephone man wonder what he's still doing in this business. :bang: ev its like everyting else in this world if you got the money to buy more bandwith then use 711 it obviously has better voice quality, if not do what the rest of us poor folk do less bandwidth and change the Codec to 723 or 729 (711 works great at my house as long as no one gets on the internet and the phone is the only thing on) the things we have to sacrifice.

OK more bandwidth or like i said get a good QoS router and give the voice packets priority over the data. After all it doesnt matter if an email turns up 10min later but voice is real time you get annoyed when a conversation has loads of delay.