No there is no federated XMPP Client for Android that supports video calling. Federated because there many proprietary XMPP Clients that do so, but they work only within their own network.
The reason because there is no such XMPP client is pretty simple: Jingle (the XEP which is used for XMPP video calling), is pretty new and most XMPP libraries don't ...
GTalkSMS (Google Project Page) does what you want (and much more).
Edit: After actively developing GTalkSMS, I decided that it's time to spawn a new project called MAXS. See my second answer.
Note: According to the FAQ I have to disclose that I am involved into GtalkSMS. GTalkSMS is an open source GPL licensed Android app. Everyone can contribute.
Not sure if this question is on-topic on Android Enthusiasts. But I work with XMPP and Android, so here is my answer:
As Lie Ryan already stated, a handover from one mobile cell to another is almost always transparent to the TCP stack on Android devices. But there are situations where the IP of your Android device will change. This are typically GSM/UMTS &...
If XMPP is not a must have you should check out MightyText app and Chrome extension.
I use it every day. You don't need to have your phone near you because you see SMS messages and you can respond from the app. You can even initiate a phone call from the extension (web app).
As far as Android is concerned, they're the same app, and Hangouts is just a new update for Talk which happens to change the user-facing name. (Apps also have a package name, which is how Android decides if they're the same app.) It works like any other update: it completely replaces the old version in your phone's internal storage. Like any other update, ...
About the statement
The quoted statement is just plain wrong. Android (or it's memory management component) does not prevent any app from keeping a stable connection to any kind of network service (e.g. XMPP).
You only have to deal with fact that Android will kill your process if it's under memory pressure. But the same manager that did kill your service (...
I'm not an expert in mobile networking, but AFAIK the TCP stack should handle mobile handover transparently, application programs should not need to be aware that the mobile network layer are switching from cell tower to cell tower. From the application program's perspective, there is just one continuous connection.
The only reason I can think of about what ...
MAXS (Modular Android XMPP Suite) does what you want, and much more. You can reply to incoming SMS messages or send them via XMPP. All you need is a standard XMPP client on your PC.
Note: According to the FAQ I have to disclose that I am involved into MAXS. MAXS is an open source GPLv3 licensed Android app. Everyone can contribute.
A bit late to answer this question but of late, a few FOSS XMPP apps have emerged for Android that have video chat feature:
Jitsi - Already covered in another answer, but app is still in aplha.
Cisco Jabber for Android - Never tried this, but appears to support XMPP, though its not FOSS. Also not sure whether it supports federation or is just a walled ...