ADSL Modems.

[Ejector]

I am about to buy a ADSL modem, I have a question though about voip, can all of them do it? I am getting totally different info from the salesmen.

Also, isit really fine to get a single port modem and just split the Ethernet cable?
THX

[airborne_artist]

All the modem does is turn the packets (the chunks of data) into frequencies that go down the copper to your exchange, where (or close by) there will be a DSLAM (a digital subscriber line access multiplexer) that takes your data and that of all your neighbours and then pushes the data on to the internet motorway.

VoIP puts voice into those packets, which go onto the network just like any other packet. The modem does not know if its handling voice, video or email.

If you are connecting one PC you can plug that PC direct into the modem, and that is connected to the wall socket. If you want to connect multiple PCs then you would normally plug the modem to a router (or buy a combined modem and router, which is more normal now) and then you can plug probably up to 4 PCs into that. Or you could buy a wireless router combined with an ADSL modem and then use as many PCs as you like around the house without any further cables.

If you like trailing leads, this (http://www.novatech.co.uk/novatech/specpage.html?LIN-AG241) would be fine, whereas for wireless you might choose this. (http://www.novatech.co.uk/novatech/specpage.html?LIN-WAG3B)

[BDiONU]

Amazon are doing a good deal (http://www.amazon.co.uk/exec/obidos/ASIN/B000G3JTV2/?tag2=hotukdeals-21) on the Netgear DG834N RangeMax NEXT Wireless ADSL Modem, Router for £99.99 inc delivery including a free Netgear WN511B Rangemax NEXT Cardbus Adapter.

This kit complies with Draft 802.11n specification.
DG834N Features: Constant connection to stream, download & transfer files * Simultaneous connect to multiple Internet services & online media * Speeds of up to 270 mbps * 5-in-1: Modem, Router, Firewall, 4-port Switch, Wireless Access Point * No need for separate modem; plugs directly into ADSL line * As always, with NETGEAR's Smart Wizard™ installation is eas * Touchless™ WiFi security easily 'locks-down' your network * Complies with Draft 802.11n specification * Works with existing wireless network devices (802.11g & b)

Box Includes: # DG834N RangeMax" NEXT Wireless ADSL Modem Router # Power Adapter # Ethernet Cable # Phone Cable # ADSL Phone Filter # Resource CD # Installation Guide # Warranty/Support Information Card

WN511B Features: Complies with draft 802.11n*, backwards compatible with .11b/g WiFi * Delivers stable, application enhancing connections using Steady-Stream technology * Interoperates at up to 270Mbps with other products powered with Intensi-fi * Ensures optimal performance with internal antenna design

Good future proofing :)

BD

[airborne_artist]

While the Amazon deal is good value, I'd have to say that I have had a 66% failure rate with Netgear USB wifi adaptors, and another Ppruner recently posted here that Netgear were very poor to support his troubles.

[Saab Dastard]

ADSL modem, I have a question though about voip, can all of them do it?

Absolutely NOT!

A bit of clarification is required. airborne_artist is correct in saying that The modem does not know if its handling voice, video or email. However, you must have software / hardware in place to create VoIP traffic in the first instance! Many solutions allow you to use a PC with appropriate hand / head set to act as a "softphone" - e.g. Skype. I use a softphone via VPN to my company's PBX. In these cases, the modem is just passing packets out to the network.

You can also buy devices that sit on your home network and allow you to connect standard phones to them - the devices act as hardware "gateways" to a VoIP phone service (e.g. SIPgate). Again, the traffic flowing in and out of them is passed out to the internet by the modem, which doesn't care what the packets contain.

You can get ADSL modems that combine this VoIP functionality with their role as ADSL modem. Usually you can attach 2 standard (POTS) phones to them, and one of the VoIP ports will fail over to the standard analog PSTN if the internet service fails, or there is a power cut.

is it really fine to get a single port modem and just split the Ethernet cable?

You CANNOT split an ethernet cable - you must install a hub or switch to provide more than 1 downstream connection from a single upstream port.

HTH

SD

[FakePilot]

There's plenty of routers that have ADSL, cable, or even dialup interfaces for connection to the internet.
Then you plug this router into your home network and if everything is configured right all the devices on your home network can get to the internet.

I have a bunch of Netgear stuff. All units required patches before working right. After that they've been fine. Simple for some, a pain for others.

As for VOIP, two considerations apply:

1. Bandwidth
2. Latency


Bandwidth is how many seats you have.
Latency is round trip time. If there is bad weather, over-booking, malfunctions, crashes etc latency will be increased by hold-times or increased to infinity (crashes).

ADSL and Cable have enough bandwidth to handle VOIP. If latency is a problem, either your ISP can fix it or they can't. You'll have to change ISP/technology.

I assume by splitting a cable you mean ethernet hub.

And there's no such thing as a digital signal. :)

Good luck.

[IO540]

There is potential for confusion here.

A few years ago, an "ADSL modem" would be just that: a modem which connects to the ADSL line at one end (basically, plugs into the BT master socket) and would provide an ethernet (RJ45) connector at the other. One popular example is the D-Link 300G+ and I have two of those right here (they work well).

But: while such a modem would be all that's needed to give your PC internet connectivity, it left it wide open to the internet. The average time to getting infected, via such a connection, would be measured in minutes. (About the same as if accessing the internet via a plain 56k modem, actually...)

Then "modems" started to get more clever. D-Link brought out an "identical" box called the 300T which was a modem but also did NAT (network address translation) plus had a DHCP server. It was actually an 80x86 PC chipset inside, running the usual ripoff Linux code which most today's consumer IT gear is based on. Such a modem - effectively a full NAT router but with only one ethernet port; most consumer routers have four ethernet ports - protected the PC pretty well.

A lot of people bought the 300T and tore their hair out trying to make it work, not realising that its extra functionality needs configuring correctly.

Today, few normal people deliberately use separate ADSL modems, but the animal survives in the form of a cheap and dirty USB-attached modem which is bundled with the very cheap broadband packages. It uses USB rather than ethernet to make the config more trivial.

Most smart consumers today buy an ADSL router which normally incorporates the ADSL modem internally, and gives you four ethernet ports, plus usually a wifi access point too. These boxes are about £50 and everybody and their dog makes them.

The only time one would use a standalone ADSL modem, like the old 300G+, would be if using a more high-end router or firewall or a VPN box or whatever and these don't normally have built-in ADSL modems.

[Ejector]

Thankyou for the tips and advice.