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asak

join:2007-08-22
Katy, TX

1 edit

3rd party voip on Comcast cable modem

I just got Comcast installed at my new home with high speed internet and voip from Comcast integrated in the modem.
I also brought with me a 3rd party voip solution that I hooked up to my router. This voip device was used on this same router in my old house without any problems (different ISP). Now it seems the Comcast modem blocks traffic from my voip device, it is not able to connect at all.

Could this be due to some ports being blocked, or will there be issues with 2 voip devices using the same line?

Is there a way that I can see the configuration in the modem to try and figure out if traffic is being blocked?
And can it be modified?


pandora
Premium
join:2001-06-01
Outland
kudos:2
Reviews:
·ooma
·Google Voice
·Comcast
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Re: 3rd part voip on Comcast cable modem

I'm using a 3rd party VOIP provider via Comcast HSI in Danbury Connecticut without any problems. I provide my own cable modem. I just double checked it as this post was typed, and it is working without any problems.
--
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."


asak

join:2007-08-22
Katy, TX

I suspect in my case the problem is the modem from Comcast. So that may explain why it is working for you.



espaeth
Digital Plumber
Premium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2

»Comcast High Speed Internet FAQ »What ports does Comcast block?

Those are the only ports that should be blocked. I'm running an Asterisk server on my Comcast connection without issues, and I have a leased modem.



Howwww

@comcast.net
reply to asak

Re: 3rd party voip on Comcast cable modem

How did you connect the "3rd party VoIP solution"?


asak

join:2007-08-22
Katy, TX

1 edit

said by Howwww :

How did you connect the "3rd party VoIP solution"?
The voip device is connected to the router, and the router is connected to the modem. This worked great at my other house. The modem only has one connection so I dont see any other way to do it.

To be a little more specific, the modem is connected to the wan port of the router, the voip device is connected to a lan port.

Kearnstd
Space Elf
Premium
join:2002-01-22
Mullica Hill, NJ
kudos:1
reply to asak

maybe the QOS of the emta blocks links to Vonage type services.
--
[65 Arcanist]Filan(High Elf) Zone: Broadband Reports



CableTool
Poorly Representing MYSELF.
Premium
join:2004-11-12
reply to asak

What is this "3rd party solution"? Does it work differently then any ther VoIP service? What is the "device" you connected to it?
Have you bypassed the router?
--
CableTechs.org/"Horrible People with Integrity"


asak

join:2007-08-22
Katy, TX
reply to Kearnstd

said by Kearnstd:

maybe the QOS of the emta blocks links to Vonage type services.
Tnx for the comment, unfortunately I have no idea what that means


sturmvogel
Obama '08

join:2008-02-07
Houston, TX

You may want to:

1. Assign the VoIP device a fixed IP, e.g. 192.168.1.30 or at least note from the DHCP logs what IP it has.

2. Put this IP in the DMZ of the router

3. Reboot the VoIP device

4. Check that the IP is still the same for the VoIP device
--
Treason is a matter of dates


asak

join:2007-08-22
Katy, TX
reply to CableTool

said by CableTool:

What is this "3rd party solution"? Does it work differently then any ther VoIP service? What is the "device" you connected to it?
Have you bypassed the router?
I am no expert on this, to me it seems to be a normal voip device. It has an internet connection and 2 phone connections. Normally I just hook it up to internet and connect the phone and it works.

The actual device is a Linksys box, I will have to check the details on it when I get home.

I used this setup with my previous ISP so there shouldnt be any problems going through the router. I could try and connect it directly to the modem and see if that helps. It has an internal hub so I could place the voip device between the modem and the router, could be worth a try. Initially I didnt think that would be possible because the modem would only accept a device with a given mac address. I have later learned that you just need to reboot the modem for it to accept a new device.

asak

join:2007-08-22
Katy, TX
reply to sturmvogel

said by sturmvogel:

You may want to:

1. Assign the VoIP device a fixed IP, e.g. 192.168.1.30 or at least note from the DHCP logs what IP it has.

2. Put this IP in the DMZ of the router

3. Reboot the VoIP device

4. Check that the IP is still the same for the VoIP device
I am not sure why this would be necessary because it has been communicating through the router for over a year without any problems, the only change is the ISP.

I believe it must be a contraint in the modem that prevents it from functioning. But I dont know what it is or how to fix it.

asak

join:2007-08-22
Katy, TX
reply to asak

This seems to be my 'voip device'

Linksys SPA-2102

»www.linksys.com/servlet/Satellit···rWrapper



CableTool
Poorly Representing MYSELF.
Premium
join:2004-11-12
reply to asak

[BQUOTE=asakI am not sure why this would be necessary because it has been communicating through the router for over a year without any problems, the only change is the ISP.

I believe it must be a contraint in the modem that prevents it from functioning. But I dont know what it is or how to fix it.
[/BQUOTE

FWIW, something working for a year, two years or two days prior really doesnt mean much. People use VoIP with EMTAs, Ive never heard of a reported issue. The CHSI port on the EMTA does nothing different then a regular modem.
--
CableTechs.org/"Horrible People with Integrity"



sturmvogel
Obama '08

join:2008-02-07
Houston, TX
reply to asak

said by asak:

said by sturmvogel:

You may want to:

1. Assign the VoIP device a fixed IP, e.g. 192.168.1.30 or at least note from the DHCP logs what IP it has.

2. Put this IP in the DMZ of the router

3. Reboot the VoIP device

4. Check that the IP is still the same for the VoIP device
I am not sure why this would be necessary because it has been communicating through the router for over a year without any problems, the only change is the ISP.

I believe it must be a contraint in the modem that prevents it from functioning. But I dont know what it is or how to fix it.
I have seen issues with a Vonage and a different VoIP provider boxes on the same network. I believe the Vonage box would reserve some ports for itself and then the secondary VoIP box would be stuck with no dialtone. Maybe that is what is happening between the VoIP device and the Comcast VoIP service.
--
Treason is a matter of dates

priller

join:2000-10-20
Gainesville, VA

3 edits
reply to asak

said by asak:

said by Howwww :

How did you connect the "3rd party VoIP solution"?
To be a little more specific, the modem is connected to the wan port of the router, the voip device is connected to a lan port.
The cable goes from the ROUTER LAN port to the SPA2102 WAN port ... not the SPA2102 LAN port. Is that the way you have it?

COMCAST MODEM-----ROUTER WAN | ROUTER LAN-------SPA2102 WAN

This should just be plug-and-play.

asak

join:2007-08-22
Katy, TX

Well, since you ask, I will have to double check that, but I agree, it should be easy plug-and-play. Maybe I put it in the wrong port on the voip, I hope I did, it would probably solve the problem


asak

join:2007-08-22
Katy, TX

1 recommendation

reply to asak

My mistake, I had the internet cable in the wrong port on the voip device
My apologies to Comcast for suspecting them