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Note: This review was originally posted on the Michigan Telephone, VoIP and Broadband blog

In yesterday’s installment of this series we discussed the internal router and other networing capabilities of the Atcom AG-188N (sold in North America by CIGear). The one thing that had me a bit puzzled was the implementation of VPN Tunneling. I’ve since been informed that the UDP method of VPN tunneling was implemented for a specific customer, and only works with that customer’s servers. However, the LT2P method does use standard L2TP, but without IPSec, which means it’s not a secure tunnel (there is no encryption used by default with L2TP). The most likely reason for using an L2TP tunnel would be to overcome NAT firewall issues, if for some reason you can’t use the IAX protocol and must use SIP instead. I’ve since added some information to yesterday’s article that includes a link to a blog post that shows how to setup an L2TP server on a Linux box. I’d still be interested in hearing from anyone that actually gets this working, since I haven’t really had the time to experiment with it yet.

Anyway, here are my final thoughts on this unit:

Let me state at the outset: I’m highly impressed with the AG-188N. Please keep that in mind as you read the paragraphs below, because reviews often tend to focus on areas where a product does not meet the reviewer’s expectations. In the case of the AG-188N, my expectations were met and for the most part, far exceeded. The one area where that was not the case was the documentation, and I’ll talk about that in a moment. But in my testing, this unit performed at least as well as any other VoIP adapter I’ve used, and I actually perceived the audio quality to be better than what I hear when using the venerable Linksys/Sipura adapters.

Atcom AG-188N

Atcom AG-188N

The Atcom AG-188N is a solid, well-built unit in an attractive charcoal-grey case. It’s very similar in size to the popular Linksys PAP2, and could be a drop-in replacement in any situation where only a single line (phone port) is required. What most impressed me during my testing was that everything I tested worked at it was supposed to, although not always exactly in the same manner as it would on a Linksys adapter (the need to press the star key to complete a 3-way call being one example). The device supports up to two SIP accounts, but in addition it supports one IAX account (something rarely found in a VoIP adapter in this price range), and you can also connect a PSTN line to the PSTN port on the back to use for calls to emergency services, local calls, etc. If a call comes in using any of the supported methods the phone will ring and you can talk, but call waiting does not appear to work “across technologies” (that is, if you’re on an IAX call and a call comes in on one of your SIP accounts, the device will report BUSY rather than giving you the call waiting beeps).

Call quality is excellent, although out of the box the incoming receiver volume was a bit low, but that was easily adjusted in the device’s configuration. I had no problems using this device with an Asterisk/FreePBX server, it worked as expected and was easy to configure (I daresay easier than the Linksys/Sipura adapters I’ve set up in the past). It does not have as many configuration options as the Sipura, but the settings that are missing are for the most part ones you’d probably never change from the defaults anyway. Actually, about the only settings I really wished for that I did not find were the ability to manually tweak certain tones (in particular, the tone that is sent when you leave the accidentally leave phone off the hook — this unit just provides a fast busy signal at roughly normal volume, which isn’t going to alert anyone that the phone is off the hook) but I’m probably the one person in 1,000 that would even care about that.

Honestly, I’m surprised that this unit hasn’t gained greater acceptance among VoIP users and service providers. Probably the greatest drawback of the unit is that many buyers will compare this with the Linksys PAP2 and notice that the PAP2 has two phone ports, while the AG-188N only has one. But on the other hand, the PAP2 does not support the IAX protocol, and does not include a router with DHCP support and a NAT firewall, not to mention QoS and VPN tunneling, if you can figure out how to configure the latter two. The Atcom AG-188N supports all of this, at a very reasonable price.

The documentation that is provided with this unit, to put it charitably, could be much better. No printed documentation is provided at all, but the included mini-CD contains documentation on several Atcom products including the AG-188N. Unfortunately, it’s in .doc format, which may not be readable if you don’t have Microsoft Word (although there are free online services that can convert .doc files to other formats — Zamzar comes to mind, but there are many others). You can go to the manufacturer’s web site to find PDF versions of the documentation, but at least in the case of the AT-188N, that documentation appears to be older than the .doc files on the disk. You may find that reading the previous articles in this series fills in some of the holes in the documentation.

Two specific issues with the documentation are that 1) it was apparently poorly translated from Chinese, with numerous spelling, punctuation, and syntax errors, not to mention being borderline incomprehensible in a few places (although it’s far from the worst translation I’ve ever seen), and 2) It is silent in some places where it should be more explanatory. For example, there’s an entire section of the manual on QoS (Quality-of-Service) configuration, but it’s titled “VLAN implement” (so many users would have difficulty finding it) and worse, it really doesn’t explain which of several possible configurations should be used in any given situation. For example, if you are using VoIP but you also have a computer (or a switch with multiple connected computers or devices) connected to the LAN port, how do you make sure that the VoIP packets get priority? That’s the sort of thing that needs to be explained in clear, easy-to-understand language.

And, there are some settings on which the manual is inexplicably silent. Worse yet, the entire section on VPN gives such sparse information that I sincerely doubt that anyone could figure out how to set up a VPN tunnel without getting additional clarification. It doesn’t help that they picked two of the most obscure VPN methods to support – one that’s used only by a single customer (though they don’t mention that in the manual) and the other an implementation that you rarely see anymore (L2TP with IPSec is somewhat common, though still not nearly as popular as some other methods, L2TP without IPSec much less so, although in a perverse way that may be a blessing in disguise – everything I’ve read about IPSec indicates it’s kind of a bear to install). I’m told that Atcom actually has a working OpenVPN implementation, but that it won’t fit in the flash memory and RAM of the device.

But really, none of this will matter to the typical user – there is a Quick Start Guide on the mini-CD that will be enough to get the average user going (or, you could refer to the previous articles in this series!) using IAX or SIP. Most of the router configuration on the AG-188N is fairly self-evident — if you’ve ever set up a router before, you shouldn’t have any difficulty with the one in this device. The places where things get somewhat complicated tend to be mostly places where typical users would fear to tread anyway.

If I could make a suggestion to Atcom, it would be this — For the next iteration of this device, please consider the following: 1) Enough memory for proper support of additional VPN tunneling methods, including OpenVPN, 2) More than one LAN port on the back of the unit (I know this will make it a bit larger, but you already have the AT-188N for those who need the smaller form factor) – it would be good to have at least four LAN ports, 3) the ability to select whether each individual LAN port is tunneled or not tunneled (when a VPN tunnel is active), 4) AT LEAST two phone ports, preferably four (if for no other reason than to make your device competitive with all the other two-line units), 5) Simpler QoS setup — build some default profiles for various situations, or better yet, let users assign QoS priorities on a per port basis (phone ports would default to high priority, LAN ports to medium priority, but each could be changed by the user with simple “radio button” selection), 6) A “greener” power supply — the “wall wart” you’re supplying with the AT-188N throws off too much waste heat (EDIT: And as noted, the “wall wart” that I received failed after approximately seven months’ continuous use), 7) And PLEASE, get someone who is a native English speaker to write or edit the English version of your manual (using proper grammar, spelling and punctuation!), and make sure you document ALL the settings on EVERY screen.

But even with whatever faults it may have, I think that any buyers of a single-line VoIP adapter (ATA) would be extremely happy with this device. It truly delivers more value than you’d expect for such a low price. When the worst thing you can say about a unit is that the documentation could be improved (and how many other products suffer from the same problem nowadays?), that’s really not much of a criticism.

One other thing that surprises me is that the sort of people who like to hack routers and/or network storage devices, and install rewritten and improved firmware, haven’t discovered this unit. When you consider all the energy that’s been put into modifying the firmware and then developing software packages for a device like the Linksys NSLU2, I’d have to think this device would be at least as attractive for that purpose. Sure, it doesn’t have any USB ports, but it’s a network connected device, which means that potentially it could store anything too large to fit in RAM on a network-attached storage device. Maybe the Atcom folks would not appreciate me mentioning the possibility that the firmware could be improved upon, but since the unit does have telnet access I have to think there’s a good chance it’s running some form of Linux “under the hood” — although I could be wrong about that — and I’m just a little bit shocked that those who enjoy digging into the internals of this type of device haven’t (yet) found the AG-188N attractive.

This is a device that really needs additional exposure among the VoIP community, which is one reason I wanted to review it. Sometimes it’s hard to get “word of mouth” going on a new device, but in my opinion this one deserves it. It’s a great, well-built device in any case, but with the ability to use IAX protocol and to tunnel its SIP connections via L2TP, you have two ways to handle those tough situations where most other adapters will connect to your server, and you can make their phone ring, but you only get one-way audio (or even no-way audio in some cases).

I’m going to close this article, and this series, with the list of features and specifications for this unit, from CIGear’s web site, but with the caveat that they probably got this from the manufacturer and I don’t believe it’s 100% accurate (just one example: Both this list and the AG-188N manual say that “Reverse polarity” is supported. But there’s no setting to turn it on or off, and I can tell you that it doesn’t appear to be on by default). So if a particular feature is really important to you, look back through the the screenshots in the previous articles of this series and if you don’t see that feature mentioned, there’s a chance it might not be implemented. This is just another example of a disconnect between the documentation and the actual unit.


Enterprise, small office and residential applications

Key features:
Support two sip servers running at the same time.
Redundancy sip server support.
Support T.38 fax function
Support IAX2 protocol
NAT, Firewall.
DHCP client and server.
Support PPPoE, (used for ADSL, cable modem connecting).
Support major G7.xxx CODEC.
G.165 compliant 32ms echo cancellation
E.164 dial plan and customized dial rules
Support Lifeline.
Call Forward, Call Transfer, 3-way conference calls
Call ID display
DND(Do Not Disturb),Black List,Limit List
Reverse polarity
Voice prompt
Increase Vlan and automatically upgrade configuration file encryption function
support IAX2 and FAX
Increase the time zone function

Data Features
Static/Dynamic WAN IP Addressing

Web, telnet and keypad management.
Adjustable user password and super password
Upgrade firmware through HTTP, FTP or TFTP.
Telnet remote management.
Upload/download setting file
Safe mode provide reliability

Two RJ45 ports, one for WAN, one LAN.
One RJ11 PSTN port for lifeline
One RJ11 FXS port for analog phone.

Data Networking:

MAC Address
TCP:Transmission Control Protocol
DHCP:Dynamic Host Configuration Protocol
PPPoE:PPP Protocol over Ethernet
SNTP, Simple Network Time Protocol
STUN – Simple Traversal of User Datagram …
MD5 Message-Digest Algorithm
DNS:Domain Name Server
RTP: Real-time Transport Protocol
RTCP:Real-time Control Protocol
Telnet:Internet’s remote login protocol
HTTP:Hyper Text Transfer protocol
FTP:File Transfer protocol
TFTP:Trivial File Transfer Protocol

Call control /voip Features
SIP RFC3261,RFC 2543
Tone generation and Local DTMF re-generation according with ITU-T
G.711(A-law or u-law)
AGC(Auto Gain Control)
G.168/165 compliant 16ms echo cancellation
AEC(Auto Echo Cancellation)
VAD (Voice Activity Detection)
CNG(Comfort Noise Generation


Electric requirements
Voltage: 9V ~ 24V
Power adapter: output DC 12V/450 mA

Operating requirement
Operation temperature: 0 to 40° C ( 32° to 104°F)
Storage temperature: -30° to 65° C (-22° to 149°F)
Humidity: 10 to 90% no dew

Regulatory compliance
CE, FCC part 15

Thank you to the folks at CIGear for their patience in answering my questions as I wrote this series of articles!

Disclosure: CIGear provided me with an Atcom AG-188N for review purposes, and allowed me to keep it after I was finished writing this series, and for that I am most grateful.

Previous Installment | Next Installment

Articles in the series: Review of Atcom AG-188N IAX+SIP ATA (VoIP adapter)

Part 1 – The unboxing
Part 2 – Initial setup using IAX
Part 3 – Setting the time and configuring outbound dialing
Part 4 – Setting up SIP, and securing the adapter
Part 5 – Networking and Internal Router
Part 6 – Final Thoughts and Summary Review
Part 7 – Addendum

7 Responses so far.

  1. […] Part 1 – The unboxing Part 2 – Initial setup using IAX Part 3 – Setting the time and configuring outbound dialing Part 4 – Setting up SIP, and securing the adapter Part 5 – Networking and Internal Router Part 6 – Final Thoughts and Summary Review […]

  2. […] Part 1 – The unboxing Part 2 – Initial setup using IAX Part 3 – Setting the time and configuring outbound dialing Part 4 – Setting up SIP, and securing the adapter Part 5 – Networking and Internal Router Part 6 – Final Thoughts and Summary Review […]

  3. […] Part 1 – The unboxing Part 2 – Initial setup using IAX Part 3 – Setting the time and configuring outbound dialing Part 4 – Setting up SIP, and securing the adapter Part 5 – Networking and Internal Router Part 6 – Final Thoughts and Summary Review […]

  4. […] Part 4 – Setting up SIP, and securing the adapter Part 5 – Networking and Internal Router Part 6 – Final Thoughts and Summary Review Part 7 – […]

  5. Never says:

    Yes, AG-188N supports both SIP and IAX2 is good for VoIP. Actually there is another advantage of AG-188N is it is with BYPASS which it could make IP call and PSTN call with one normal phone only.

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