Phone service

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Bert Russell
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Phone service

Post by Bert Russell » Sat Sep 24, 2005 9:13 am

Is anyone out there using Voip, and if so, how is it working out?
Thanks for any answer forthcoming.

Newz2000
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Re: Phone service

Post by Newz2000 » Sat Sep 24, 2005 1:43 pm

I'm using vonage and I love it. If you decide to use it, let me refer you. You'll get a free month and I will too.<p>When I describe it, I call it "cell phone quality or better," because at times the sound is a little metalic to the person on the other end. You, the VOIP subscriber usually hear crystal clear sound, even if the person on the other end hears a little distortion. I've noticed that when I upload it causes the metalic sound. A sure fire way for me to ruin the quality is to run BitTorrent - for example, when a recent Fedora release came out I set it to download the DVD image. While it downloads it constantly shares the portions you've already downloaded with others and it really ruins my voice quality. <p>Usually the sound quality is unnoticable from a regular phone line.<p>My broadband connection is 3Mb/s receive and 256Kb/s send. The voice uses up to about 100Kb/s. There's a setting to lower the bandwidth requirements but it caused a noticable loss in quality.<p>I like it and I recomend it to others. It seems to work great for me and my family and I have no complaints.

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philba
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Re: Phone service

Post by philba » Sat Sep 24, 2005 2:55 pm

I use vonage with the linksys adaptor. It is, for the most part, pretty much indistinguishable from a "regular" telephone line. The reason I use quotes is that most phone calls are transformed to the digital domain and transmitted that way. You just don't see it happening.<p>You do want to have a good internet connection. I have comcast @> 1.5M bps. I've heard that people with lesser connections may see some degredation in voice quality but i don't know the specific bit rate points where that happens.<p>Phil

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Externet
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Re: Phone service

Post by Externet » Sat Sep 24, 2005 6:08 pm

Hi.
I would say the connection speed should not be that high for voice. :confused:
At my workplace we stream at 48Kbps and less for FM quality, and that is stereo ! A decent dialup connection is usually good enough. Does it really need that much bandwith ? Am curious...<p>If you want to hear, choose your station:
http://www.opticodec.net/
Use the best speakers you can hook up to really enjoy, or connect to your HiFi stereo.
Miguel
- Abolish the deciBel ! -

Newz2000
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Re: Phone service

Post by Newz2000 » Sat Sep 24, 2005 6:33 pm

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Externet:
I would say the connection speed should not be that high for voice. :confused:
At my workplace we stream at 48Kbps and less for FM quality, and that is stereo ! A decent dialup connection is usually good enough. Does it really need that much bandwith ? Am curious...
<hr></blockquote><p>I was surprised too. I set up voice over ip (Lucent Definity PBX) in one of my offices a few years ago. We used one of the GSM compression codecs and had excellent sounding results in the range of 16 - 48 Kb/s. That's why I tried lowrering the audio quality on mine to use less bandwidth. However, the sound quality dropped noticably for the person calling me.<p>I attribute this to one of the following:
a: I don't know (most likely)
b: the processing in the little Linksys box I bought isn't powerful enough to do real time GSM compression
c: Internet latency introduces some serious hurdles
d: SIP or whatever they use for the transport uses more bandwidth on top of the voice compression
e: Security has been added to the protocol to keep people from hijacking voice packets as they travel through the Internet<p>My Lucent system was on a private network with a latency of something like 12ms. The Vonage system certainly has to tolerate something like 50 - 90ms at best and probably something like 90 - 150ms in reality.<p>If there is some type of security, and I'll be surprised if there isn't, it could add a substantial amount of data to the voice payload. Since these linksys boxes don't need any special configuration to work behind a NAT router, I'm going to guess they create an SSL tunnel between the linksys box and some place at Vonage. Internet radio stations don't need to worry about that and therefore use less bandwidth.<p>Again, just guesses. I haven't tried hacking mine and I don't plan to.

Mike
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Re: Phone service

Post by Mike » Sat Sep 24, 2005 8:10 pm

I've had one question about VOIP. Today we got a paper in the mail with a great deal on VOIP - 200 bucks/yr, unlimited US and Canada Calling.<p>I have DSL and I was wondering, if we subscribed to that, would I be able to get the box with the phone jack on back and plug it into my wall jack so any phone in the house can be picked up and used, and also ring, so basically it's identical to regular analog phone service?

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philba
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Re: Phone service

Post by philba » Sat Sep 24, 2005 11:55 pm

the reason that it takes more bandwidth is due to the way the encoding happens. real-time compression has some pretty severe time constraints - you've got to get that packet digitized, compressed and sent in milliseconds or the delays become perceptable. Network transport adds significant delays as does reconstruction on the other end. A lot of encoding algorithms trade off compression for speed.<p>Relax the real-time requirement and you can squeeze a lot more bandwidth out.

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