[PLUG] telephony cable modems

[Mike Connors]

>
> I have just started with Comcast.  I am presently renting an Arris
> TM402P for $7/mo.  I am looking to purchase my own modem.  Comcast
> lists many compatible modems
> (
> http://mydeviceinfo.comcast.net/mydev.php?tier=-1&h=0&d3=0&s=v&so=0&e=0&sc=536
> ),
> but it is clear that not all the listed units match what is needed.  I
> assume that only units designated "Telephony" will be suitable, as I
> am getting voice service through Comcast.  This restricts the choices
> to Arris (23 units in the list, but if I lump NCS, IMS, and SIP
> together, the count is 9.)
>
> Questions:
> What do the NCS , IMS and SIP designations mean?
> What does the D3 column in the modem list mean?
> None of these show support for IPV6.  Does this matter?
> Any Linux-related issues with these units?  The Arris TM402 seems to
> be working fine.
>

These are all architecture, protocol and call signaling standards for the
delivery of voice network (PSTN) and ip multimedia services over cable
modems.

Some of the functionality this provides is that in theory you can take a
SIP phone and just plug it into the cable modem network as an endpoint.
Vonage uses SIP to provide voice over ip telephony services. The
PacketCable spce
adds SIP internetworking support for the development and delivery of
services such as instant messaging, IPTV, video telephony.

Note that most of these services can already be delivered via IP and the
Internet. Cable providers want their services to be the way people interact
with the Internet. It's their way of trying to get control of the end
customer. Which is why they've been fighting with VOIP providers and large
multimedia content delivery providers like youtube, netflix, google, et al.

IPv6 compatibility only matters if for one if you are employing IPv6 on
your computers or two if your service provider stops supporting IPv4. Most
service providers just started supporting IPv6 in the past couple of years.

My personal preference would be to use a SIP trunk provider and a SIP
softphone on my laptop and smart phone. I've played around with google
voice & pbexs.org over wifi on my android phone. It works okay for short
calls but I have a cell phone as backup.

The real benefit of rolling SIP into the cable modem specs is that the
network is able to provide end to end quality of service for telephony and
video. On the public internet, you can mark packets with QOS parameters but
no devices are obligated to honor those QOS settings. So the quality
fluctuates due to congestion, equipment failures, etc.