Win one of three new IAX phones!

April 22, 2009 by Garrett Smith

A few days ago Insider Cory Andrews leaked information about a new VoIP phone that landed at VoIP Supply which supports the IAX2 protocol. For quite some time Asterisk lovers and open source nuts have been clamoring for a quality IAX compatible VoIP phone.

Well, today we’re proud to unveil the new Citel C4110 and announce a contest that could land you one of these bad boys for FREE (before anyone else) and a custom IAX GIAX (Eeks Geeks) T-Shirt!

Before we get to the contest, let’s look at the C4110.

The Citel C4110 is a stylish business class VoIP phone with two line appearances, dual Ethernet ports, Power over Ethernet, SIP and IAX2 protocol support. The C4110 can also be configured via a web gui or auto-provisioned using TFTP.

All of this for only $99 USD! (Plug: We are now accepting pre-orders. Supply is limited.)

And let’s not forget the IAX GIAX (Eeks Geeks) T-Shirt:

With that out of the way, it’s on to the contest.

The theme of this IAX phone contest is, “Why do you use IAX protocol?”

In order to enter the contest, you must do one of two things (or both if you want two chances):

  1. Leave a comment below about why and or how you use IAX protocol in your VoIP deployment(s).
  2. Write an article on your website, post on your blog, tweet on your Twitter or post a note on your Facebook about the differences between IAX and SIP with a link back to this contest.

This contest will run until Monday, April 27th at 5pm EST. At that time, the Insiders will meet and pick three winners (probably from a hat).

So if you’re interested in getting your hands on an FREE Citel 4110 before others can even buy it and your custom IAX GIAX T-Shirt spend 5 minutes of your time leaving a comment below about why and how you use IAX protocol or use your own site to let the world know about the differences between IAX and SIP!

More from: Asterisk Garrett Smith


  • Dave Fullerton

    I use IAX to connect Asterisk systems in different locations together. The reason I use IAX over SIP is primarily because it is easier to use when routing over the internet. I only ever have to worry about opening one port in my firewalls and it is easier to prioritize traffic by referencing that one port. I also use IAX trunking to cut down the bandwidth footprint when multiple channels are in use over one IAX connection. For me, IAX is easier to set up and easier to maintain.

  • I use IAX mainly for remote offices and sites where we don’t control the routing or firewalls, as it’s very easy to traverse without any special configuration. Only one port needs to be opened and setup. So much win compared to SIP. Like Dave said above, it’s easier for us to manage and setup IAX than SIP in most cases.

  • I use IAX because it goes through NAT and firewalls.

    It also has some neat features like :
    zero config encryption – handy for shared wifi
    built-in link stats monitoring
    bandwidth saving ‘trunking’ mode
    Blocked in fewer countries/networks than sip

    I like IAX because the RFC has fewer pages than the _number_ of SIP/STUN/RTP RFCs

    I’d wear the Tshirt with pride (I got a mention in the RFC) Although you _have_ to give one to Mark and one to Ed Guy.

  • I use IAX2 over SIP because i can avoid the problems of setting up the NAT config, i also use IAX2 because i don’t have to use the RTP ports, i can send dialplan modifications through the URI and i have less header weight so i don’t use that much bandwidht.

  • Tony Sumrall

    I find it’s easier to configure IAX to provide more reliability than SIP.

  • Luc

    SIP is great, but IAX is cool!!! Setup it and forget it!


  • I use the IAX2 protocol for network monitoring. I use IAX2 registration packets to test connectivity to my client’s IP-PBX installations and if a condition requires attention, myself or my support staff is immediately alerted with a telephone call. More often, my clients have support tickets solved and closed before they are even aware of a problem.

    What to read about the differences between IAX2 and SIP? Check out:

    Thanks Garrett

  • I use IAX when people specifically demand it, but we’re trying to curb that these days. Since IAX is horribly broken from both a stability and security perspective, we carefully limit its availability, and only for server-to-server connections where we have a static IP. I look forward to all routers being brought up to today’s standards so that IAX is no longer needed to address bad NAT implementations.

  • Mike Metzger

    If for one reason alone, to avoid the horrors of SIP / STUN over NAT’d networks, especially when traveling…

  • Bill

    One UDP port to deal with, less firewall and NAT headache. I’ll take whatever IAX I can get.

  • IAX’s simplicity and ease of use are the reasons for me.

  • My favorite use of IAX is conserving bandwidth by packing multiple media streams (calls) into each UDP frame (connection). Doing so means that each supplemental call increments the bandwidth usage only by the nominal bandwidth of the codec itself (instead of codec plus IP overhead)! In this way you can pack hundreds of g.729 calls from your bandwidth-rich ITSP to your favorite “self-service voice applicaiton” (self hosted) using only a moderately fast connection!! Very nice!

    p.s. frIAX you out when you see how many calls you can pack onto your T1, T(n). Sorry, I couldn’t resist.

  • Michelle Dupuis

    Whenever possible we deploy IAX handsets/softphones because of the simplicity and compatability with strict corporate network restrictions. In federal govt and hospital environments we’ve seen competitors go down in flames because they assumed SIP’s broad range of ports would be supported but inside and across the perimeter.

  • Jack

    We use IAX for trunking between two Asterisk boxes (only one of which is ours) – it is more reliable than SIP and because our system is behind a NAT firewall, it’s much handier to use IAX than SIP.

  • With this new phone we can have a phone that can easily be taken anywhere and plugged in to a broadband connection, with NO configuration required AT ALL on the firewall, in almost all cases you can start talking instantly. And you can have as many phones as you like on the one connection without the need for a remote server or IPSEC tunneling!

  • We use IAX to interconnect Asterisk servers in faraway places. Works great. Less filling.

  • We use IAX to enable remote connections to connect to our asterisk systems in countries where SIP is prohibited. Also works great whenever a client has NAT issues.

  • I use IAX2 to connect my asterisk server to my service provider’s asterisk server, then use sip for my home PBX.

  • I use IAX both for connecting remote sites and mobile clients that can connect to server either from office or home. Major here is connection simplicity. For offices major is traffic efficiency and built-in encryption.

  • IAX2 is useful in many ways, not the least of which is the fact that is uses a single port for signaling and RTP. Firewalls that would really get in the way of SIP pass IAX2 traffic easily, and it’s not hard to keep-alive the opening to allow for seamless inbound calls too.

    IAX2 trunking is also really valuable. If you have more than a couple simultaneous channels, the overhead saved by not wrapping each channel with it’s own controls is not insignificant.

    We use IAX2 to trunk between sites, and to run systems from behind firewalls that are either unmanaged/closed or not accessible to us (i.e. foreign government run, etc.)

  • Mark Petersen

    I always use SIP phones, as the customer can always use the phones with a different provider, as SIP is the industry standard.
    I see no reason to use IAX on the phones
    as the selection is very limited and running a mixed setup i just asking for trouble
    and SIP work just fine if you are in full control of the network

    I hope I win 😉

  • I currently don’t use IAX for many implementations, just when a VOIP provider has it available, and we can reduce the amount of open ports to connect to them.

    Too many of the iax compatible soft/hard phones do not have the business look that many clients demand, but with these products we can deliver the benefits of IAX and still provide the business look.

  • fabricio

    Uso iax (trunk iax) para conectar servidores de telefonia IP, es un protocolo muy bueno para esa funcion especifica, y los internos que uso son sip, trabajan muy bien, es un buen protocolo, se lo recomiendo a las personas a usar esta clase de protocolo, ya que tiene un buen resultado

  • Tom Schmitt (TomS)

    Currently, I use IAX2 between PBXs as it is easy to configure and very efficient in handling the call overhead. IAX2 can use the same trunk connection to handle multiple conversations thus again ease of use.
    IAX2 only requires a single port 4569 UDP to be available so Firewall configurations are simplified.
    IAX2 is well suited to traverse NAT implementations compared to the SIP setup.
    IAX2 uses the same codecs so you get comparable quality of speech.
    I like IAX2 for softphones as they make great and simple access possible.
    I use SIP for most internal phones because of the availability of SIP telephones. I have not found a IAX2 quality physical phone to test. I believe that this new phone might just fill the bill.

  • Great way of getting a good blog even more press….nice

    Well, we use IAX in places where VoIP is blocked (UAE for example) we allow ex-pats who are missing the BBC i Player / cheap VoIP Calls back home etc… to use a VPN / IAX solution to allow them access to blocked websites.

    I will add your IAX phone contest page to my twitter page:

    How do we find out who the winner is?

  • Ariel Batista

    I use IAX2 to connect our asterisk to asterisk setups. As we use a few servers for our call centers. It’s used for the main trunk lines between them. At each location we either have 4 or 8 PRI lines setup and trunk them with IAX2.

  • VoIP Consulting

    I use IAX only for remote offices and sites where we don’t control the routers or firewalls, as it’s very easy to configure it, also using softphones like zoiper. Only one port needs to be opened and setup. SIP is OK but IAX is perfect to solve this problems.

  • Jacinto Casaravilla

    I use IAX to connect Asterisk PBX in different locations together. The reason I use IAX is primarily because it is easier to use when running over the internet. I only ever have to open one port in my firewalls and it is easier to prioritize traffic by referencing that one port ( QoS). I also use IAX trunking to cut down the bandwidth consumption when multiple channels are in use over one IAX connection.

  • hercross

    I use IAX primarily due to its simplicity when it comes to setting it up, its ease of joining switchboards, because there are no problems with nat.
    Today, only use it to connect Asterisk PBX, one with another, as a single port on the firewall we have soluiconado, and because to date there is no decent terminal to use the IAX.

    Will have to prove this model to check its operation, if there is the push we need to move to IAX to the terminals, both remote and local.

  • nick

    we use iax2 to connect our two switchvox servers over an mpls network. works great in this configuration but i’d like to test it outside the firewall as well.

  • There are three main reason why I think IAX is a better protocol to deploy in certain environments compared to SIP + RTP.

    The first reason is the firewall issue. For users with simple firewall setups (“nothing goes in, everything goes out”) SIP can, in theory be as easy to get going as IAX. However in practice this is often not the case. The simplest part of SIP is the protocol running on port 5060. This is seldom a issue, but as soon as you involve RTP, problems will sooner or later rise and create a lot of confusion and iritation.

    When I was working at a (now defunct) ITSP we had some big customers with some “real” firewalls. More than once security personnel “tuned” the firewall and put a too strict limit on the number of ports open for RTP. Who got the blame when the VOIP service did not work? Yes – the ITSP.

    In comparison the IAX protocol only need one port. Everything is tunneled inside the the IAX protocol: call control information and the voice data itself.

    This brings me to the my second reason on why IAX may be better to deploy in certain environment: Overhead.

    Yes – network overhead is an issue.

    It has been a while since I checked the numbers, but as far as I remember the overhead using RTP is around 90 bytes per voice packet compared to IAX. May not seems like a great deal – but do not remember that in one second speech there can be as many as 50 packets (20 ms each). So we now have 4500 bytes overhead pr second! Maybe not very much for a small company – but for a big company with hundreds of concurrent calls this adds up. Seen from the technical point of a ITSP – usin IAX make much more sense than to use SIP.

    Of course, from a business point of view SIP is the major player.

    The third reason is not necessarily very valid – but it is worth taking into account: IAX is so much easier seen from a implementation point of view than SIP + RTP.

    Granted, SIP can be used, and is used, for much more than IAX is today (video springs to mind).

    But SIP has become extremely complex.

    One of the reason SIP was invented or created was because that H.323 was complex.

    I have not much experience of H.323 except to not like it. If SIP was a supposed to be a simplification compared to H.323 – the the current crop of SIP RFCs are not proving this. I have read more than one place that SIP is now becoming as complex as H.323.

    I know I only had 3 reasons – but for added bonus I’ll put in a 4th reason.


    Security on SIP is not straight forward compared to IAX. I have observed more than once that VoIP (that is SIP based) was not possible to deploy even inside a organization due to internal firewalls and internal security policies. I am not talking about SRTP or SSIP as being the problem solver – just the number of ports that need to be open.

    Even if one enable encryption on the IAX protocol, it’s still running inside it’s own tunnel. In fact – enabling encryption on IAX does not implicate the need for amending firewalls the same way that one need to do if using SSIP and SRTP.

    A story from CeBIT in Hannover this year to prove this very point: My company have created a secure call solution which uses SIP + RTP. For all practical purposes we emulate the tunneling features of IAX with the added encryption thrown into the equation. One of our visitors to our CeBIT booth got a presentation of our solution and exclaimed that: “Wow – no more firewall problems like we now have with our customers”. It’s a sorry state for a protocol suite when one have to tunnel everything to get around network roadblocks for voice communication.

    On eBay you can find IAX based handsets. I have tried several of them – but they are all lacking something (see my blog entry on the GXV3140 on the Far East Syndrome). However, I have great hope for the Citel 4110. My main reason is that voipsupply is carring this phone. They are probably not plauged by the Far East Syndrome compared to IAX phones sold on eBay the last years.

  • Kris Stark

    Why use IAX – quite simple really:

    Top 10 reasons to use IAX

    1.Your firewalls are restrictive.
    *** With IAX, you only need one port open.
    2.You don’t like managing multiple ports.
    *** SIP is a mess with required ports.
    3.You run over odd networks.
    *** IAX is great at traversing even the most complex setups.
    4.Your mobile users need to connect too.
    *** IAX can traverse NAT devices easily.
    5.You need to save your bandwith.
    *** With IAX trunking, multiple voice streams can use a single control stream.
    6.You can get rid of your SIP proxies.
    *** Multiple IAX devices can work behind NAT devices without proxies.
    7.You can simplify your network configuration.
    *** Build it – IAX will work.
    8.You want to use a protocol specifically designed for Asterisk.
    *** Asterisk SIP support is good, but IAX was built for Asterisk.
    9.IAX is cool.
    *** Isn’t it?
    10.You don’t need a SIPpy cup anymore.
    *** IAX is all grown up now.

    Also on Twitter under jkstark…

  • Jim

    We at the Sylvestri Mind Control Institute used SIP for years amongst our different locations. The stress of willing the RTP streams through the routers to their destinations just became too much; especially for our receptionist. Thanks to IAX we can now focus on other things, like your desire to award us the Citel C4110. You do want to award us the Citel C4110, don’t you? Don’t you? Yes, you do.

  • Jim

    We at the Sylvestri Mind Control Institute used SIP for years amongst our different locations. The stress of willing the RTP streams through the routers to their destinations just became too much; especially for our receptionist. Thanks to IAX we can now focus on other things, like your desire to award us the Citel C4110. You do want to award us the Citel C4110, don’t you? Don’t you? Yes,

  • Carlos

    We use IAX because in my country SIP and H.323 are blocked by the goverment!!! To use voip we have two options
    1. Use a vpn with every branch
    2. Use IAX 😛

  • I’ve used IAX2 for four reasons:

    1. Because it leaps tall firewalls & NAT routers in a single port.

    2. Because is conserves bandwidth when trunking between servers.

    3. Because it support encryption with minimal setup headache.

    4. Finally, we use it because it’s different, and so not so likely to be the target of some kind of malicious attack.

  • securevoip

    I use IAX because it goes through NAT. Prior to IAX, session border controllers were an option. Do you know how much SBCs cost?!?

    I have great hope for the Citel 4110 for teleworkers. Selling SBCs to avoid the horrors of SIP over NAT’d networks is not easy.

    I have always found it ironic that SIP (from the INTERNET Engineering Task Force) has more difficulty with NAT than H.323 (from the International TELECOMMUNICATION Union); it would seem that INTERNET people should get NAT (and networking in general) better than TELECOMMUNICATION people.

  • Ed

    I use IAX because it is easy to configure. It needs onlyt one port and works thru my corporate firewall with worrying about rtp and all the other nasty setting that go along with it. We use IAX2 to communicate with several telecommuters around the country.

    IAX2 rules!!

  • Chris

    As Apple says, “It just works”. SIP is a nightmare in the real world. I have been using cheap Asian IAX2 phones for some time, I am sick of pleading with Polycom to make a decent phone with IAX2!

  • Chris

    Actually I just took a look at the instruction manual for this phone at

    This phone apears to be made by ATCOM since the firmware is virtually identical in terms of user interface. I hope they fixed some of ATCOM’s bugs before making this version. VOIP supply please contact me if you want to know some of my ATCOM issues.

  • IAX is much easier to configure to go through NAT, and as such these IAX phones are ideal for telecommuters who need to link up to the main office. We only need open the 4569 port to the server and don’t have to worry about all of the additional ports that SIP requires.

  • Bryan Cole

    Anyone know why the IAX protocol in this phone was not given a line appearance button? Or did I set something up incorrectly?

  • Whenever you think of VoIP. the first name comes is SIP. When you feel SIP is not giving you the proper voice data on any given condition, then IAX can give you the proper solution and best voice quality. There are proof of this above statements

  • When I lost a week of my life to trying to connect multiple Elastix (Asterisk-based) boxes with Cisco 7960s while traversing multiple NATs and dealing with a few Sonicwalls– I decided that it was time to learn something about IAX2.

    I have one thought: “Why the heck did I ever waste time on SIP?!?!?!”

    IAX2 phones are a BREEZE to set up. They could care less about NATs other than making sure the port forwarding for its SINGLE port is working.

    IAX2 trunks between Asterisk boxes were a little trickier, but once I got it working, it works like a champ!

    No more sip_nat.conf for me! Woohoo!

    I am disappointed to see so few IAX2 phones out there, but I’m sure we’ll be pushing them for our clients– and we’ll be proud to but them from VoipSupply. 🙂

  • ,..] is one another relavant source of information on this issue,..]

  • Can someone pls help me set up an OEM iax2 devices, I procured it from a vendor in China, the vendor was hardly helpful when it came to technical support, the devices support IAX2, SIP, and Proxy SIP, I really need help badly as I have invested a large sum in the devices (I purchased 10 devices) and I also deposited a large sum of $$$s into an IAX reseller account, I have to use IAX as it is not blocked into the destination countries, any help would be greatly appreciated.

    thanks a million in advance


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