Is there a Voice/Sound Quality Difference between IP vs Digital Handse

[chefwong]

http://www.tek-tips.com/viewthread.cfm?qid=1233719

If the IP phones are on own vlan, QOS on switch (Cisco 35xx), cat6 grade cabling from desktops to switch (my environment) - Is there ANY noticable voice quality from either a handset or speakerphone on the digital handsets vs. the IP handsets ?

 

[jameshen]

We changed phone systems, going from digital phones on our old Nortel platform to IP phones with the new IP Office.

The main complaint from our users was that it sounded like they were talking in a "well", or "tin-can". We knew that our network was fine, there was no echo, jitter, delay etc. So, we bumped up the compression mode to G.711 ULAW 64K and it sounds great. Just don't count on running 8k compression.

 

[big70]

TDM sounds better as IP but with G711 it,s good enough for most custemors.

IP makes everything more flexibele and is a new hype, but digital is beter and more reliable.

Greets Peter

 

[chefwong]

Does the same Apply to VOIP circuits. I CAN sometimes tell if someone is on a VOIP circuit or not. It just has a slight tinnyness to it. I am not sure however if it's the circuit, call quality/QOS of the VOIP circuit, handset or maybe even headset on the other talking party side of things.

Then again, I am using a Polycom SIP setup for my needs right now behind a private network and call quality has been just great on G711.


Does anyone feel the same ?
I am debating right now how to bring my new voice circuits in.
Call/Sound Quality is a factor as well.

Static Flex T
Dynamic T
or even
sip trunking via a IAD behind the private network

 

[carpetflyer]

We have IP phones connected to a hosted VoIP provider (so basically a VoIP circuit) on a T1. We also use the T1 for our data. QoS is done on our LAN switch (computers are connected to IP phones) and QoS is done on our edge VoIP gateway router.

I have to say the quality is really bad. Occasionally users experience choppy sounds and they also hear echos of themselves. I would say, about 10-15% of our daily calls are bad.

I am in the process of getting a new phone system that uses a PRI trunk. Sure it will cost a lot more each month versus a hosted VoIP provider, but we would rather have a "crystal clear" phone connection than deal with choppiness.

 

[chefwong]

Carpetflyer -

Is your hosted voip voice circuit from your T1 (data provider)or just 3rd part. There is certainly a call quality difference between the two. Alot of factors into play - is the voice on it's own vlan, qos on switch and bw, etc.

Just some things to keep me in mind.

 

[carpetflyer]

its a hosted circuit by our T1 provider. They claim to do QoS on their network as well.

Voice is on its own vlan, qos is done on the switch and on our voip gateway.

It sounds really good when we talk to each other in the office. Sometimes I check the stats of the phone during a conversation and the ave jitter is only 8. However, on certain calls I do see packet loss.

The worst type of calls we get with voice quality are with cell phones. Speaking cell phone -> cell phone sounds a lot better than our IP phones -> cell phones.

How are you connected?

 

[chefwong]

I am debating but it may be Dynamic T1 (voip voice going back into IAD/PRI) or just traditional intergrated T .


You got me curious now as I was leaning on the Dynamic T1....which essentially is a VOIP voice but on the transit provider as opposed to public internet transit.

Was you router or switch up to snuff ? Who was your T1 provider providing the circuit ? Or here is the kicker - were they INDEED hosting their own voip service or was it *rebranded* but the voice/voip traffic was actually going out to someone else on the internet.

 

[carpetflyer]

They said they were hosting their own VoIP, but when i checked the SIP server it was another company that is contracted under them. Speakeasy (

http://www.speakeasy.com)

is the company.

Our switch is really good, a Procurve Gigabit switch with everyone running at 10/100. Our network traffic is also generally low.

A coworker of mine just called someone in Hawaii and said he had a tough time hearing the conversation!

 

[chefwong]

Are they reselling the T1 service ?

Here is the deal - once VOIP hits' the public internet, no QOS can be maintained , regardless of how you have your OWN internal network. Thus , some of you issues may stem or all of your issues may stem from that.

I am not a SE gurus, but it is well known that their service is not up to par with more expensive transit providers...latency, etc.

Personally, if I'm running VOIP on any type of line that is a business, it had preferably be a Tier 1 or Tier 2 (with decent peering) etc providers as opposed to Speakeasy IMO.

 

[carpetflyer]

They are actually resellers of Covad's T1 lines. I know their VoIP service isnt that great but they have really good tech support. That was one main reason why I went to them. However, I would rather have excellent phone quality than great tech support.

What kind of VoIP providers are you using?

 

[chefwong]

I am not sure on the whole SE/Covad relationship.
I thought SE has their own pops, etc. I have read blurbs awhile back where their T1 service is frame relay over DSL.

For data traffic, I am a big proponent on the usual big dogs like Spring, Global Crossings, MCI (verizon business - NOT Verizon), Qwest etc. Some of these do offer hosted VOIP.

I've been using Vonage at home since they 1st came out and I have had no issues whatsover. Sure, some bumps along the road but it has been really stable for the last 2.5 years easily ! However for a business, I still think VOIP has not matured enough that I would put in into ANY business environment.

Just one mans opinion. I hate it when someone calls me on a bad connection and both parties are now *struggling* to hear each other rather than hang up. Business = $$$ and at the end of the day I would rather spend more $$ for telecommunications services than be attracted to the $$ savings.

 

[carpetflyer]

Yes I totally agree! I wish I came across these forums before I went ahead with the hosted provider. It looks great on paper, especially for our company since we have never purchased a phone system before.

Now I am in another dilemma:

we are looking into a IP PBX system and am stuck between a pure IP system versus a digital/hybrid system.

In terms of deployment, doing to a pure IP system is a lot easier because I only have to replace the phones. Going to a digital system will require us to add more Cat 3 phone drops + move our cubicles around to access the voice outlets. However, going digital would be great in terms of maintenance because voice and data are not longer converged.

I have asked the techies on this forum and its pretty much split. What do you think?

 

[chefwong]

Have you done a TCO between going digital systems vs. Pure IP. Cost of cabling versus costs of keeping a managed network for the IP phone systems. Take all these into consideration as each has it's own pros and cons.

Just short of material being a slight upcharge, if you end up pulling cable, pull 5E unless you think u may move when you're lease is up.

 

[carpetflyer]

Hmm so i can use 5e for digital? cool didnt know that. our current office has a few cat 3 drops for voice so i figured that was the way to go.

as for a TCO, never done one of those before. I will try to do those for practice. Thanks for all your help!