VOIP from scratch II - Hardware

Unlike softphones, discussed in the first instalment of our beginner’s guide to VOIP, hardware solutions enable you to use the regular phone(s) you are presumably accustomed to use. There are three major solutions that could enable your home phone line to be routed over the Internet.

They are ATAs, hard or IP phones and router-ATA combos.

If your needs are simple, an IP phone might suffice. However, because it combines a high-quality business phone and an ATA, be prepared to spend more than you would spend for each consumer-grade device separately. The newer phones also come with colour displays, enabling desktop videoconferencing. This might be slightly more than you need – for video conferencing you can use your computer. We will not be discussing this option. We linked to an Amazon list below, in sources, in case you are interested what is available.

ATAs and an IP phone

voip routers

VoIP routers (which we called “combos”) place QoS emphasis on the voice data stream, sometimes to the point of being detrimental to their general routing abilities. However, those (VoIP) routers that run linux have an amazing ability: they can run Asterisk.

TIP: If you’re only trying to get started with VOIP, go directly to “choosing your ATA”, as the next fragment is more advanced and of little use to you.

To install Asterisk you do not actually need a VOIP router. What you need is a good Linux router with at least 16 MB or RAM + USB; 32 MB is better. Here is a summary of the necessary steps, from Mango’s labour (toao, in sources) and the dslrep forum:

  • install Tomato firmware with USB support on the router (you might be able to do it with another distro as well)
  • slim down and simplify your install through a combination of the following
    • init script: rmmod ext3 / rmmod wl / killall –9 buttons
    • remove all logging & bandwidth monitoring
    • disable telnet and enable SSH (this is for security)
    • disable file sharing & disable FTP server
  • attach the USB drive after enabling core USB support, USB 2.0 and Ext2/3, then SSH into router, delete partition make a new one & reformat in ext 2; make it automount – in run after mounting: sleep 15 / [ -d /mnt/USB ] && mount /mnt/USB /opt
  • wget http://www.toao.net/pub/VoIP/optware-install-ddwrt.sh -O - | tr -d '\r' > /tmp/optware-install.sh
  • then sh /tmp/optware-install.sh
  • install asterisk: ipkg update / ipkg upgrade / ipkg install asterisk16
  • disable logging and modify modules.conf in /opt/etc/asterisk to contain as few modules as possible
  • add to Run after mounting: cru "a" "asterisk" "*" "*" "*" "*" "*" "asterisk"
  • to access Asterisk command line, type asterisk –vvvr

Alternatively, you can get the mega version of DD-WRT to run on the WL-520gU with a USB flash drive. The idea is that you flash the router with the mini/standard version of DD-WRT and then mod it so it boots from the flash drive (which has the mega version on it).

Tomato-supported routers:

  • Linksys WRT54G (v1-v4 only), WRT54GS (v1-v4 only), WRT54GL (v1 & v1.1), WRTSL54GS (no USB support)
  • Buffalo WHR-G54S, WHR-HP-G54, WZR-G54, WZR-HP-G54, WZR-RS-G54, WZR-RS-G54HP, WBR-G54, WBR2-G54, WVR-G54-NF, WHR2-A54-G54, WHR3-AG54 (WHR-G125 Supported in the ND version of Tomato)
  • ASUS WL-500g Premium (no USB support), WL-500g Premium v2 (use the ND version), WL500GE, WL520GU (1.22 and above, see FAQ, no USB support)
  • Microsoft MN-700 can work with v1.14 perfectly except the "Buttons and LED" function are not supported.
  • SparkLAN WX6615GT
  • Fuji RT390W
  • Dell TrueMobile 2300
  • D-Link DIR-320

choosing your ata

An ATA can not only serve as a an interface between your home telephone wiring and your VOIP provider, but it can also take various roles once you set-up your Asterisk system. An ATA consisting of both FXS and FXO ports (such as SIPURA 3000 or a VOIP Gateway) is more useful than one containing only FXS ports.

Another consideration is codecs. If you need to fax, the VOIP adapter must support T.38 (although similar, SIPURA 2100 supports it but PAP2T does not); for HD voice (wideband audio), it needs to support G722. Polycom is one of the few manufacturers supporting it. Cisco SPA 501G 8-line IP Phone does support HD voice, as well as some Cisco, Grandstream and Siemens IP Phones, but if your VOIP provider does not support it or if it is not supported by intermediaries, it might get downgraded along the way.

One interesting development is that MagicJack plans to replace its existing USB device with a GMS femtocell. If you have a GSM phone, you will be able to connect to MagicJack and make free phone calls at home through your mobile phone connected to a GSM ATA. The announcement was made at CES by Dan Borislow in January 2010.

I ended up choosing the PAP2T, mainly because it is so widely supported – important back then, for a beginner - and it has all the basic features I needed. I was under the mistaken impression that it supports faxing, which it does not. If that is important to you, choose Sipura 2100. You will also be able to travel with this device and use VOIP in hotels. The Sipura SPA-3000 can be used as both ATA or PBX.

There are peple selling unlocked PAP2 for $50, but I recommend you get it from a reputable retailer with free shipping, such as Amazon, NCIX or Dell. I tried to stay away from any Skype solution as they are proprietary and most require a working PC, which partly defeats the purpose of an ATA.

update to the latest firmware

Upgrade PAP2T firmwareAfter making the necessary physical connections, update to the latest firmware. You find it on the product page (see link below). It should generally correct problems and fix bugs.

After downloading the firmware archive, run the included .exe file which should cause the “Confirm Upgrade..” window to pop up. The example will not look like yours, because we took the screen capture after performing the update – if it does, you do not need to upgrade.

The new firmware version is printed on the Title bar, while the current version installed in your unit is listed in “Software Version”.


securing the adapter

Most people hold the mistaken belief that anything over the Internet is inherently less secure than the “real” world. I happen to disagree. Though the Internet enables a virtual unknown to rob you blind from the antipode, your POTS line can be easily tapped with an FM transmitter at the demarcation point without you ever knowing it and there is very little you can do about that. Armed with knowledge, however, you can make it much harder for anyone to tap into your virtual conversations.

PAP2T passwords There is no point in securing your voice communications if your LAN is insecure. As such, if you use wireless, make sure you don’t use WEP, as even a 5 year old can break it these days. Use WPA2; and follow our [yet unpublished Whistling] guide to deploy it securely. Know that even WPA2 is not as safe as you might think, but it is still far better than WEP. Placing any computer or device (including your VOIP adaptor) in DMZ is a bad idea and you should avoid it. Finally, to secure your adaptor, set up passwords even if it is behind your firewall, as illustrated in the screen capture.

When securing anything, remember that security is generally inversely proportional with convenience. The more secure something is, the less usable / useful it becomes. We all have our own individual sweet spot – the trick is to find it. If you choose to completely disregard security, you may find that although initially things are easier, they could become progressively unusable due to infections with malware; if you feel that security is paramount, you may end up with a system that is unusable or too difficult / painful to use, to the point where it starts to resemble traveling by plane.

In the next episode we'll look at choosing a VOIP provider and then configure our ATA with them.

Sources / More info: VOIP IP phones @ Amazon, ata-voip-info, voip-secu, wiki-PAP2, cisco-linksys-voip-router-Q&A, linksys-voip-config, pap2t-prod-page, 2talkIAX-v-SIP, spaconf, toao-pap2t-review, toao-asterisk-router, forum-asterisk-router, dd-wrt-flash, wideband-ip-phones, polycom-hd-voice, yt-pap2t


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