There are dozens of Jabber-compatible apps for iOS, and I would assume the same for Android. The two that come to mind are Beejive (I think it's a separate Jabber-compatible app) and IM+.

Thanks bvrooman. Tried those and just never got them to work! been trying since the first fricken iPhone and every iteration since. Can not find any info on getting any client to work. Its very frustrating and I can't be the only fool on the planet trying to do this.

@lifelike, I've been using Beejive since it first came out for the iPhone with our iChat server and it has worked well. It was a little tricky to get the account setup correctly on the device, but once I figured out the settings it has worked well. I think I had to set the SSL option to TLS to get it to connect to our server. The biggest negative to the software at the time I got it was it cost $20.

Thanks mpermann. I'll keep trying. At least I know that it CAN work.

I remember working on this in early revisions of iOS. XMPP, being a traditional messaging protocol, isn't push-aware and requires a constantly open connection, which doesn't work well with how iOS handles memory for applications and network connections. You'd need somebody or something to hold-the-door-open so to speak, and a go-between for push awareness which is what services like beejive does.