Routers Overview

You will need to use a router (pronounced ‘out’ router not ‘oot’ rooter) with your VoIP service. Why? You can only have 1 device connected to your broadband connection unless you use a router. A router (as its name suggests) routes (or shares) the internet connection to multiple devices.

If you want to start using VoIP, you will need to buy a router if you don’t already have one.

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Purchasing Advice

If you haven’t bought a router yet, have a good think about your current and future needs. Routers can have wireless connectivity or wired only connectivity. They can also come with inbuilt ADSL modems and inbuilt ATAs too (or both). If possible, buy a router that has Quality of Service (QoS) capability. More information on QoS is covered further down this page here. Here is a table of features and benefits:

Features	Benefits
Wireless 802.11g	Allows you to use the router to connect to other wireless internet devices such as wireless enabled laptop PC. 802.11g is old technology now and has a maximum speed of 54 Mbps. Your broadband internet connection is much slower than this, so this is fine for surfing the internet. If you want to stream video from your desktop PC to your home media centre however, 54 Mbps is the absolute minimum speed you will need (faster is better). Particularly since the maximum speed can only be achieved when you have maximum signal strength. Because it is old technology, these are relatively cheap at about $120.
Wireless 802.11 Pre-N with MIMO	As above, but operates up to 108 Mbps, so is better for video streaming. Will have no impact on VoIP quality or Internet speed over the 802.11g. Because it is newer, it will cost you more (say $200+)
Inbuilt ADSL Modem	As you could imagine, this is only good if you have ADSL broadband. Depending on your broadband service, you may get a modem for free, so it may not be worth buying another modem as part of your router. The advantage is it is one less device to go wrong, and because it is integrated with the router, you are less likely to have any modem/router set up issues.
Inbuilt ATA	As with the ADSL modem above, you are less likely to have issues between your ATA and router if you buy an integrated device. At the time of writing, there were no ATA/router combined devices that also have PSTN integration.
Inbuilt ADSL Modem and ATA	Has the combined benefits as the two devices outlined above, plus the additional benefit of PSTN fallback. However you can only get the PSTN fallback on a router with an inbuilt ADSL Modem as there are no routers that do this that are designed for cable internet.

Refer to the VoIPHardware page for information on some of the more common VoIP enabled routers. There is no model information on this site about non-ATA routers as there are too many models to mention. The key thing to do is determine if you want your ATA to be integrated with your router or separate. Read up on purchasing advice on the home page for more information.

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Routers – the Cause of all Evil

Well it’s true. If your VoIP Service Provider (VSP) tells you that there is nothing wrong with their service and the problems you are having with your Quality of Service (QoS) are related to your router, then they are probably right. VoIP Analogue Telephone Adaptor (ATA) boxes work just fine, and most VSPs provide a good enough service that there is no reason why the quality should not be acceptable to you. The only thing that can really go wrong is the outgoing voice traffic is hindered in accessing the internet, or the incoming voice traffic is hindered in accessing your ATA. When this happens, it is almost always your router that is causing the problem. If you want to test this, bypass your router and connect your ATA directly to the internet modem and see if the problem goes away – it is almost guaranteed it will work. You can’t actually do this if you are using Telstra Bigpond as Telstra requires you to log onto the ISP with a username and password. Your ATA can’t do this for you and needs to be connected to a router so that the router can log on to the ISP first.
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IP Addresses

One of the main functions of a router is to allocate an IP Address to each hardware device that is connected to the router. Your Internet Service Provider (ISP) uses a huge router to allocate an IP Address to every computer that connects to the ISP. Once it has allocated an address to your computer, they can talk to each other. It’s a lot like a phone number – if no one knows your phone number, other people can’t communicate with you.

Now if you buy a router for home use, it is actually your router that connects to the ISP and your computer no longer connects directly with the ISP as before. The ISP therefore allocates an IP Address to your router instead. Your home router then allocates an IP Address to every hardware device on your home network.

Each router has a range of addresses it can use, normally by changing the last 3 digits of the address. So your home network would have a range of IP Addresses something like 192.168.1.0 through to 192.168.1.255 Your router keeps one address for itself say 192.168.1.1 and then allocates every other device that connects to it a unique address between 192.168.1.2 and 192.168.1.255 How it does this depends on how your router is setup.

Dynamic IP Addresses

The normal operation of a router is that it will allocate an IP Address dynamically (ie at the time the address is requested). When a device connects to the router, the router will immediately look to see which of its IP Addresses are currently in use and which ones are free, then allocate one that is free. The advantage of a dynamic address is that you don’t have to worry about it and the router does it for you. This is good say when you want to plug your laptop into the router – the last thing you want to do is stuff around setting an IP address yourself. The downside of a dynamic IP address is that it can (and frequently does) change, particularly when the power goes off or when your router reboots unexpectedly.

Static IP Addresses

The alternative to a dynamic IP Address is a Static IP Address. With a Static IP Address, you manually allocate the IP address for the router. Depending on the router, you may need to reserve this IP address from within the range of available IP addresses, or make sure that the static IP address is outside the range of dynamic IP addresses allocated by the router. Refer to your router manual for more info on how to do this. You really do need to sort this out, because it is much better to have a static IP address than a dynamic one.

When you set up your VoIP at home it is preferable to use a static IP Address. This is because many features such as QoS and DMZ (refer further down this page) can give unwanted results if the address of the hardware device changes. Using a static IP Address is the only way you can guarantee that the IP Address doesn’t change.

Router Firewalls

Routers have a built in firewall to protect your computer network from the internet. The firewall is like a brick wall full of holes, and each hole can be opened or closed to stop anything getting through the holes. These holes are called firewall ports* and each firewall port is given a number. The numbers range from 1 through to 65,535. Different firewall ports are used by different software programmes to access the internet. This means that you can open and close the firewall ports based on what information you want to get to/from the internet. If you don’t open the right firewall ports for VoIP, the quality of your service will be very poor, or maybe it wont work at all.

*Note Well: There are 2 types of ports referred to when talking about routers. The firewall ports as described in the section above, and the Ethernet port at the back of the router for attaching your hardware to. On this router page I will specifically refer to them by their full descriptive name, but be aware that it is normal for them all to be referred to as ports – so don’t get them confused.

The ports 1-4 in the image above are Ethernet ports. The firewall (brick wall in the image) is configured to let traffic in (or not) by configuring the firewall ports. The firewall ports can’t be seen in this image, but can be thought of as tiny holes in the firewall that are either open or closed.

Router DMZ

DMZ stands for
Demilitarised Zone. Normally your router (and hence the firewall) sits in between your modem (ie the internet) and your home computer network. That way the firewall can control what gets through. Most modern routers have an option to create a DMZ – that is it has the ability to expose one or more devices on your network to the internet even though it is physically connected to the router. In the image below, Ethernet port 1 has been set up as a DMZ and has bypassed the firewall.

When you setup a DMZ, any type of internet traffic will be able to connect to the hardware device in the DMZ.

Router manufacturers use different methods to create a DMZ, but they normally either need you to specify the MAC Address of the device, the IP address or the physical Ethernet port address that you have the device plugged into the router.

If you setup your DMZ by specifying the IP address, it is very important that you first give your ATA a static IP address. If you don’t do this, you run the risk of exposing your computer to the internet at some stage in the future. This can happen if there is a power failure or the network is switched off then on again. When your personal network goes down, then up again, it dynamically allocates every device on the network an IP address. It is not unusual for the devices to switch IP addresses after a power failure. If this happens, the DMZ that you originally configured for your ATA can end up being a DMZ for your PC. That would be the same as not having a firewall and leaving your PC open to attack from any nasty predator on the internet. Windows XP does now come with its own firewall installed in the operating system. If this is switched on, you do have a second level of defence against a change in dynamic IP address that accidentally points to your PC. The flip side of this happening is that the DMZ you set for your ATA will no longer work for your ATA, so your VoIP service quality may turn sour.
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Port Forwarding

Port forwarding is a method of exposing your ATA
to the internet without exposing the rest of your computer network too. If you are having problems with your VoIP quality, you could try setting up port forwarding through your router firewall. You need to forward the ranges UDP 5060-5061 (used to initiate a VoIP telephone call) and UDP 16384-16482 (used to transmit the voice traffic) to the ATA IP address (Note that the VSP SIPme advises users to open ports 35000-45000). For information on how to do this, you should refer to your router manual, but it normally involves logging in to the router via a Web Browser using the admin password, locating the admin settings for port forwarding, adding the firewall port ranges as above for the IP address of your ATA, and saving the changes.

The graphic below illustrates how Port Forwarding (opening up the firewall ports for the ATA) has been enabled.

When you setup port forwarding, the internet traffic continues to go through your firewall to the hardware device, however unlike the DMZ, only certain types of internet traffic can get through. In the case of VoIP, it is VoIP traffic.

As with the DMZ,
you should set your ATA to have a static IP address if you set up port forwarding. Each router is different and the exact procedure on how to port forward varies. The site below shows all the different available routers and exactly how to set up port forwarding for your router www.portforward.com

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QoS

Some model routers allow you to give upstream bandwidth priority to your ATA by telling the router where the ATA is, and giving it priority access to the internet for VoIP traffic. To do this you need to tell the router one of the following. Either:
1. specify the MAC address of the ATA or

2. the static IP address of the ATA or

3. the physical ethernet port your ATA is connected to the back of your router ie ethernet port 1,2,3 or 4

This is called setting the Quality of Service (QoS)
and ensures that the ATA always gets priority over internet browsing
etc. NB QoS will not allow you to prioritise downstream bandwith.

How you configure QoS varies by router and manufacturer. Some manufacturers allow you to give one or more devices High, Medium or Low priority. If this is the case, then give your ATA the highest priority allowable, and leave everything else alone. There is no need to give other devices such as your PC Low priority.

Other manufacturers allow you to set how much of your up upstream bandwidth will be prioritised for a device. If this is the case with your router, you should set the upstream bandwidth as high as reasonable, ie with a 512/128 broadband service set the upstream bandwidth to 128 so essentially the ATA has first call on all the upload bandwidth. If you have more bandwidth (particularly upstream) you can leave some bandwidth for other internet services. Play around with the settings and see what works best for you.

You really need to read your router manual and/or explore the configuration settings of your router to work out what to do. If you have specific problems that you can’t resolve, try searching for information on the whirlpool forum.

For a more detailed (and excellent) explanation on QoS, have a look at the Vonage website.
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Troubleshooting Routers

What can go wrong?

There is a lot that can go wrong when setting up your VoIP service for the first time to work with your router.

ATA fails to be allocated an IP address
Can’t make a call
ATA fails to register with the VSP
Call quality is all choppy and hard to hear

The section provides tips on how to work out what is wrong.

Do you have an IP Address to your ATA?

One common problem is your router failing to allocate an IP address to your ATA. The default setting for most routers is to dynamically allocate IP addresses to any device that connects to it. What should happen is you should connect the ATA to your router, power up the ATA, and the router should allocate an IP address. Once you have connected, you can check if it has been set up correctly by going into the config screen of your router and check the DHCP clients table. Different routers call it different things – some refer to this as local network clients. You should see your ATA in the list of clients.

It is definitely better to have a static IP address for your ATA, however it is easier to set up a dynamic IP address first. Once you have it working with DHCP, then move to a static IP address.

If you follow the procedure above and the ATA is not allocated an IP
address, then you need to check the settings in your router first.

Check if DHCP is enabled.
Check the maximum number of DHCP clients allowed by your router, and increase the number if necessary.
Check that the range of IP addresses available is sufficient for another device.
Check the settings on your ATA to ensure that it is set up to allow DHCP allocation.

Firewalls

You really do need to allow your ATA to have free access to the internet on the ports it needs to use. You can do this in a number of ways outlined above. The preferred order is 1. Port Forwarding, 2. DMZ, 3. Turn off firewall*. As long as every PC on your network has a software firewall, and there are no other devices connected to your network, it is quite safe to turn off your router firewall. This should still be considered as a last resort however.

SPI Firewalls

Some newer routers come with multiple firewalls built in (ie a standard firewall and a Statefull Packet Inspection (SPI) firewall. SPI firewalls (as the name suggests) inspects every packet of data that is coming in from the Internet, and makes a determination if the packet is a threat to you (ie does it look like a Denial of Service (DOS) attack). Now this is all nice and rosy, but SPI firewalls have been known to cause havoc with VoIP services. The easiest thing to do is turn off the SPI firewall. You would have to be pretty unlucky to be targeted by net thugs, and you would normally have another firewall in your router, and probably another firewall on your PC too. The risk is low.

One thing to note is that once you turn off your SPI firewall, you have
to power down your ATA and power it back up again before the changes
will take effect.

There is more good information about SPI firewalls available here http://www.homenethelp.com/router-guide/features-firewall.asp

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Further Information

For more information about routers, or for help configuring your router, visit http://portforward.com/

Routers