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I just met with a potential new customer who has a one-year old ESI-50 system in their office. They have four IP phones working on it at another office 30 miles away. They are using CATV Internet at both ends. They've been having a lot of trouble with the IP phones, to the extent that they took on a new vendor to support them.

The new vendor came in and told them that they needed VPN routers in order to solve the voice quality issues they were having. They bought these and there was no improvement. They are sharing the same LAN drops as the desktop computers and have said that if they have anything significant going on the computer, the associated phone becomes pretty much useless.

They are now expanding the remote office and are seeking us as their new vendor to assist. They want to consider putting another 50 in at this location and use twelve digital 40 phones and a hand full of local POTS lines.

My question is: Should we insist upon separate LAN runs for the phones and computers? We need to rule out the current issue that they are having before we consider networking.

Also, is this a project for those who are not strong with ESI systems? I don't think that we'd be doing this customer any favors if we're going to be in over our heads. Any advice would be greatly appreciated.

Most of our CATV Internet here is no good for voice. For bulk traffic it's great but the quality can drop drastically for seconds at a time, which of course is unacceptable. I assume it's the same elsewhere. We always use a dedicated entry level DSL for VOIP in this situation. I've given up trying to run voice and data together over anything less than enterpise grade service.

On a the LAN with 12 users- as long as their wiring is up to standards and they have 100 meg switches I see no need for separate runs or any kind segmenting.

Ed, PM sent.

Speaking as a customer what we ran into with CATV internet was a limitation in the standard. With DOCSIS 2.0 modems they have a packet per second limitation (around 200pps I think) so even with low bandwidth, small packets you could fill your line. We use a terminal server and that was chatty enough to fill the pipe without actually using hardly any bandwidth.

Took forever to figure out. Once we did we shamed the CATV company into providing us with 2 modems for the price of one where one was for voice and the other for data. Still using VPNs we had good luck until we finally ditched them a bit after. Still some chirp and echo from time to time, but usable.

Dean

Check your codec. You might want to try G.729 and see if there is any improvement. The sampling rate is lower than G.726 and, therefore, the transmission won't be that great. The default is G.729 but it may have been changed to improve quality. Generally speaking, unless you are on a fiber CATV feed, you will have a lot of problems with the cable feed. Remember, everyone on the street can use the same feed, so your bandwidth can be all over the place and it's usually poor and slow.

Rcaman

codec on a 50 cannot be changed it is G.726

My gut feeling is the CATV is to blame. We have a few customers with mult-site (local & remote) IP phones, running them through single jacks for phone & PC. They work just fine.

The only sites we've ever had issues with call quality have been sites with CATV for internet.

You can try to check the traffic shaping settings on the router, but like a previous poster already said, one of the biggest limitations of CATV internet is there is no way to control the data between the sites. QoS is pretty much out the window once it leaves the building, for lack of a better way to describe it.

Separate jacks probably won't help the issue very much, if the data is still going through the CATV circuit.

If they are only running 4 IP phones, a single DSL line would support that just fine.

Sorry for the miss-information regarding the Codec. I usually work with the 200, 600 and 1000 and those systems allow codec changes. Hook up a PC to the network and do a speed test. That will reveal a lot about what you are getting from the cable company. Use the speed test from whatismyip.com. It is far more accurate than the Xfinity test.

Rcaman

Codec won't help at all if there is unacceptable packet loss, latency or jitter. The only thing a lower bandwidth codec like G.729 is good for is to allow for more conversations on an otherwise good connection.