Voip

You may want to experiment with it first. All the bells and whistles sound great, problem is too often the voice quality doesn't. It seems lots of small internet businesses use voip to keep costs down, but it seems to me, if I have to have them constantly repeat words, it just makes for an annoying conversation

You are probably right. It is not the cost so much as the flexibility. This winter when there was a couple of bad snow days I had to go to the office even though I have Remote Desktop and can work here at home. The problem was no way to reroute the phones with the plain old Bell service.

With Vonage, simple to log on and reroute the phones here. But since as a transportation broker the phone is the business have to be sure. It is intriguing however.

With proper hardware which uses QoS (quality of service) VoIP is as good as normal line. Using 4 lines at once would be no problem on a fast DSL connection with no simultaneous heavy data traffic. However fax over VoIP is not reliable, fax machines aren't designed for data delivered in packets. Regards, Martin

Thanks Martin,

Just remembered - the fax line would have to stay anyway since it is the line that the DSL is tied to. So that leaves just the 4 lines of which the

4th line is seldom used and there is no heavy data traffic.

I put Vonage in here at home as a 2nd line just to test and play with it and have never had any problem with voice quality. Using cable at home which is much faster than the DSL at the office.

I guess the only way to really know is to try it. Can always go back if it don't work out.

You could run a fax card in an office computer to take incoming faxes and set the fax machine itself not to answer. Then remote in to the computer with the fax card to retrieve the faxes.

I would use a business class VoIP provider and not Vonage.

On Thu, 8 Mar 2007 13:33:19 -0600, "Don Harvey" wrote in :

What kind of DSL?! There are vast differences between different types of services.

John,

Just the basic DSL - I think like 384 up and 1.5 down. I had it installed in 1996. There is no cable in this little strip office center even though the houses behind my office have cable, go figure. Cable company told me not available. So I am stuck with DSL and Satellite for TV.

Should be able to easily handle 4 VoIP lines.

On Fri, 9 Mar 2007 22:12:09 -0600, "Don Harvey" wrote in :

"Don Harvey" hath wroth:

1500/384 is what we have in the office with 5 companies sharing a single DSL line. 3 of these use VoIP service from various vendors. It works well enough but is far from perfect. It really depends on what else is happening on the DSL line. For example, I've had to impliment QoS (quality of service) to lower the priority of bulk file transfers, MS updates, and virus updates, because these were saturating the bandwidth for short periods causing VoIP dropouts. Similarly, I've had to increase the priority of VoIP service. That worked fine until I started using Skype Video, which again saturated the available bandwidth. I now have to use video after 5PM but not during business hours. One of the other business purchased a Polycom conferencing system, which worked nicely if nobody else was using the DSL, but stuttered and belched artifacts when the DSL was busy.

At this point, I'm convinced that VoIP works, but only on a

*DEDICATED* DSL line. We're in the process of setting up a 2nd DSL line for exactly that purpose. My guess is approximately 12 voice channels will be needed. I'll probably try an Edimax load balancing router to use the bandwidth for surfing, but my guess is the other users will ask me to rip it out the first time it trashes one of their phone calls.

Thanks for the info Jeff. From your description I think probably VoIP should work well here. I have 4 lines but only 3 people and for the most part only my wife and I are doing the telephone work. There is no heavy use of the internet that would suck up bandwidth.

I think what I will do is go ahead and set up a single line and use it for a while to check voice quality and ease into it. The options available on VoIP would really be an asset for this business.

Don Harvey

In that case, you'll do fine with your existing setup. The limiting factor is the outgoing bandwidth and compress scheme selected. The worst is G.711 PCM which hogs 64Kbits/sec and is NOT compressed. My

1500/256 Kbits/sec DSL line can handle 4 of these voice channels before it hits saturation. At the other end of the compression range, we have G.723, which only requires 5Kbits/sec per voice channel, but sounds awful. I should have a chart somewhere.... foundit. G.711 PCM 64kbps uncompressed G.723.1 MP-MLQ 6.4kbps compression G.723.1 AC-ELP 5.3kbps compression G.726 ADPCM 32kbps compression G.728 LD-CELP 16kbps compression G.729A CS-CELP 8kbps compression

I think you'll find that it's just as easy to setup 2 or 4 lines for the cost of not much more than a single line. A big benfit of VoIP is the incrimental cost of additional lines is minimal.

Jeff - this is the voice bandwdith, but doesnt include the IP packet over head.

G.711 is 80 to 84 Kbps. (as used at work on Cisco call manager).

The IP overhead is higher on the various compressed voice streams, since you have to send packets at 20 mSec intervals, and the IP bit stays the same size as the voice payload gets smaller.

My

when you get to G.729A or B with 8 Kbps of voice samples, you have 24 Kbps of actual traffic.

Note - the overhead varies depending on the physical link - AFAIR this is for Ethernet.

On DSL it will depend on the protocol stack used.

"stephen" hath wroth:

Sorry. I made some assumptions that I didn't bother detailing. Throw in UDP instead of TCP, silence suppression, and raw protocols. See below for numbers. A better chart would be:

Codec BR NEB G.711 64 Kbps 87.2 Kbps G.729 8 Kbps 31.2 Kbps G.723.1 6.4 Kbps 21.9 Kbps G.723.1 5.3 Kbps 20.8 Kbps G.726 32 Kbps 55.2 Kbps G.726 24 Kbps 47.2 Kbps G.728 16 Kbps 31.5 Kbps iLBC 15 Kbps 27.7 Kbps BR = Bit rate NEB = Nominal Ethernet Bandwidth (one direction)

I'm currently doing battle with a 7690 IP Phone. The phone is winning. I'm trying to convert it to a SIP phone and TFTP update hangs at 80% complete. It's probably broken.

Yep. I goofed on G.711.

Yep. I thought the chart looked a bit too simple. I was in a hurry, didn't read the associated text, wasn't paying attention, etc.

Anyway, this is the online calculator I prefer to use:

Your 24Kbits/sec is for TCP. More common is UDP requires only

16Kbits/sec for G.729b. If I tack on silence suppression, the average bandwidth utilization approached 9Kbits/sec while the peak bandwidth remains at about 20Kbits/sec.

I think (not sure) that the appropriate model for wireless is 802.3 emulation (under the link window pull down). With G.729ab, 802.3, and silence suppression, I get 9.6Kbits/sec average and 19.2Kbits/sec peak. That's not my claimed 8Kbit/sec bandwidth, but it's certainly less than your 24Kbits/sec.

Another calculator (that doesn't have silence suppression) is at:

However, it includes the note: "The results obtained from the calculator should be considered only in one direction. In half-duplex networks, like 802.11b(Wifi), you should double the estimates." which means that I also ignored the half/full duplex problem and that all bandwidth numbers I stated should be approximately doubled for wi-fi. In the "L2" pulldown menu, if I select 802.11 wi-fi, the bandwidth numbers double. Oh-oh.

Yep. 802.11a/b/g wireless is encapsulated ethernet.

Yep. My at&t DSL is PPP over ATM (RFC1483/2684). The "ATM tax" is fairly heavy. Estimating from my download speed, I get 1250 bytes through for every 1500 I send or about 17% overhead. Ouch. That doesn't show in any of the VoIP bandwidth calculators and needs to be added.

Thanks for the correction and sorry about my screwup(s).