This article is the last part in a series of articles highlighting various instant messaging (IM) clients on various pager platforms used by the deaf and hard of hearing. To read the previous article, click here.

In this article, I will give a quick overview of the Windows Mobile operating system (OS) that runs on various types of hardware. I will also discuss various IM clients (for AOL Instant Messenger (AIM), MSN Messenger - now known as Windows Live Messenger - (MSN), and Yahoo! Messenger (YIM). For the purposes of this article, ICQ is considered part of AIM.) available on each platform. IM client overviews are arranged in alphabetical order. Trial versions of most clients for these platforms are available and I encourage you to try them out before purchasing/deciding on one client. I also usually keep a second client handy just in case there is something wrong with my primary client.

Windows Mobile (MDA, Treo 750, 700wx, Dash, Q, etc.)
Windows Mobile 6.0 (codenamed Crossbow) is the latest iteration of Microsoft’s mobile operating system. Microsoft’s mobile operating system was first known as Windows CE, then Pocket PC, and now is known as Windows Mobile. (Yes, Windows CE does power Windows Mobile, but that is an entirely different discussion!) The most current version of Windows Mobile was just released - version 6.0 codenamed “Crossbow”, which is compatible with Windows Vista. Many recent devices such as the T-Mobile Dash are getting free upgrades to this new version of Windows Mobile.
To further muddy the waters, there are two major distinctions of the Windows Mobile OS - “Pocket PC Edition” and “Smartphone Edition”. The main difference is that Pocket PC Edition is for devices with touchscreens (ex. T-Mobile MDA, Treo 750, Treo 700wx, etc), while Smartphone Edition is for non-touchscreen devices (ex. Motorola Q, T-Mobile Dash, etc). Many of the developers of multi-service IM applications for Palm OS also create versions for Windows Mobile, and the applications work pretty much the same across different platforms - so don’t be surprised if some of my comments are the same.

Agile Messenger for Windows Mobile
Agile Messenger is a multi-service IM client that connects to AIM, MSN, and YIM. It is apparently free for download, but does not seem to have been updated since mid-2006. Use at your risk.
(AIM, MSN, YIM) Free, download required

AIM for Windows CE
This is a standalone AIM client for Windows CE - a little old, but you might find it functional on your Windows Mobile device. YMMV, included because it’s free, and it just might work.
(AIM) Free, download required

Causerie Unified Messenger for PocketPC
Causerie is a nice multi-service IM client that comes in two versions, “Standard” and “Premier” like the Palm and BlackBerry versions. The Premier client allows you to log into the same service twice with two different accounts (good for work/personal, etc.). Causerie also has “bots” that get you information like news, weather, movie info, etc. inside the IM application itself. These clients have a nice interface and are quite reliable, but updates come in spurts. The software is nice and easy to use. Good online support is available via their forums. The only bad thing is that you have to pay an annual fee to use the software, and this fee is pretty low because they apparently just released the “Pocket PC” version, so they say the pricing is “introductory”. No idea how long this will last.
(AIM, MSN, and YIM) $19.99/yr for Standard & $29.99/yr for Premier, download required

IM+ for Windows Mobile Pocket PC
Another multi-service IM client. The developer also produces versions of IM+ for almost every other wireless platform available, and offers crossgrades at no or low cost, making this an ideal client to use if you think you will change the type of pager you have down the road. You also only pay a one-time fee for this program. It looks like a nice program, but I did not like how the interface was set up, making it a bit complicated to use.
(AIM, MSN, and YIM all via Jabber) $39.95 one time fee, download required

imov Messenger
This is a free multi-service IM client that uses Jabber to connect to practically every IM network out there that is supported by Jabber. Jabber is somewhat complicated to master, but if you already know its ins and outs, imov may be what you’re looking for. Looks nice, especially with auto-notification of new versions.
(AIM, MSN, and YIM all via Jabber) Free, download required

Mundu IM v4 for Windows Smartphone
A nice multi-service IM client for Windows Mobile Smartphone. This latest version is much more refined than previous versions, and is much cheaper than comparable multi-service clients. It works very nicely, even though its interface requires some learning, and does almost everything you could ask for.
(AIM, MSN, and YIM) $11 one time fee, download required

Pocket MSN Messenger
This program comes with almost every Windows Mobile device under the program “Pocket MSN”, giving you access to the MSN IM network.
(MSN) Free, included with most versions of Windows Mobile devices

WebMessenger Mobile Instant Messenger for Windows Mobile 5.0
This was one of the first multi-service IM clients, and is still available for monthly or annual subscription. Works very nicely because it is a server based program. Its user interface is quite complicated to master, but it is very stable.
(AIM, MSN, YIM) $5.95 monthly, or $34.95 annual subscription, download required