We are using a CTX 670 with 2 users using ip phones. One in Indianapolis, one in Houston. They are connecting through a broadband cable connection going through a linksys cable/dsl router and are experiencing poor voice quality, especially choppiness. I am not experienced with Voip and our vendor has been no help in resolving our issue. If you can help please respond. Thanks.

I'm don't work on this system but try changing the jitter buffer to a high number if you have a setting for it. Also try changing codec to g.729a if you have that setting. This sends smaller packets so if some are lost it doesn't get so choppy

have you spoken to the installation technician?
m

I have and they don't seem to know a whole lot. Pretty much all they are saying is that it should work. And have no explanations as to why it doesn't. I would even be happy with suggestions to try but can't even get that.

Tony has a great suggestion. Try using the g729 codec. It's simple to change.

are they using VPN?

No we are not using VPN. We were told by our vendor that wouldn't make a difference.

If the BIPU isn't on a public address outside the router, you need to use a VPN. Definitely go with G.729 and increase the jitter buffer. E-mail me and I'll send you a cheat sheet for programming.

Many "broadband" connections really arent that fast. If there is interfering data traffic and the link speed is under 500 kbits/sec then just the time taken to send a data packet can cause significant delay "bumps".

Increasing the jitter buffer size can help however if the jitter is severe then you may have to use a large buffer size which can increase delay too much.

Using G729A reduces the bandwidth taken by the voice packets but would not affect the bandwidth of data traffic - hence if interference from data is the issue then you'd need to fix that first.

Larger routers support prioritization of voice over data however small consumer class routers don't tend to.

The www.voiptroubleshooter.com site has more information, plus a downloadable IP simulator that you can use to set up the scenario and try different codecs and jitter buffer settings to see what would happen

Alan

VPN is the best way to go we have found so far.

The main issue is your going over the Internet. Once it leaves your building you have no control or guarantee on not getting bottleneck in some router 2 states away.

We just purchased a Toshiba CTX670 with the VOIP card. Our provider isn't much help at all. Like others have said, they claim you just plug it in and it should work.

I'm curious as to where you change the codec. We have the WinAdmin software but I haven't seen that setting anywhere for the VOIP card. Is there another way to configure the card?

We connect our VPN via Windows XP. How would you use the phone over a VPN connection?

#1 - VPN on WinXP is just computer to computer, not a true network-wide VPN. Your VPN needs to include the IP of the VoIP card and the IP phone. I would suggest using a VPN router, Linksys and Netgear make affordable ones.
#2 - All the settings for VoIP are listed under "IP Telephony", not under card or station programming. Definitely use G.729 codec, MH216 or later software on the CTX, and increase the jitter buffer. If you or your provider needs help configuring VoIP, send me an email or reply here.

Junkman: Thanks for the quick response.

Overview: We hope to implement VoIP phones for 5 of our remote employees. They are located in different states and one is in Canada.

I have successfully got one VoIP phone working on the internal network. It works great. My next task to get another VoIP working from my home DSL connection. From doing a little research I have found I have the following options to achieve this.

1. Get a VPN router for each location.
2. Put the VoIP card outside of the firewall (I prefer not to do this – Any thoughts?).
3. Open the correct ports on the firewall allowing the VoIP traffic to reach the card. (I haven't been able to find the port numbers to try this).

Have any other suggestions?

The official word from Toshiba is that the BIPU Card Will not work behind a firewall. It has to go outside with a public IP. There are no security concerns. I have done this at various locations with no problems. The IP phones WILL work behind your firewall at home. My experience is that a linksys DSL router works out of the box. The Netgear needs to have the ports opened. I have that port information if you need it. E-mail me.

Voyager

I was going through the settings in the Network Setting Mode on the IP phone (IPT2020). What are the purposes of the following settings?

1. Default Router Address - This is typically assigned by DHCP or should I put one in? Should this be the IP address of the linksys/netgear router?

2. Admin IP Address Lower/Upper - ?

3. PASSWORD(Within 16char) - Can I assign a password at the PBX level so only phones with the correct password can connect?

Router address should be assigned by DHCP or you can manually enter the address of your router. Not familiar with the 2020, so I don't know about the other 2.

Heres my experience......

1. The router address (default gateway) is assigned by DHCP. If you are using a Netgear wireless router, you may have to assign a static IP, Subnet mask and gateway to the phone.

2. I don't know what you mean here. DHCP will assign the IP for the phone. On button (I think 12) is where you have to enter the IP address of your BIPU card.

3. I don't believe so. Anyone who knows the IP for the BIPU will be able to connect if there is an IP port programmed and noone is using it. For example, I have an IP phone here. If you have an extn 501 programmed on the BIPU and noone is connected to it, I can enter it here and use your system. The only thing you can do is toll restrict the port, assign forced account codes or delete the port.

Thats the way I understand it.