Given that you have an integrated Jabber Voice/Video web application using the functionality called "Click-to-Dial", imagine this scenario:
I have developed a small telephone directory where the number is highlighted in the form of hyperlink. So, when a user clicks on the number, a small window opens in the web application for audio video communication.
Now, to include here Instant Messaging, use Jabber IM SDK (CAXL), which is a separate Jabber SDK from Jabber Voice/Video.
CAXL uses http over xmpp and it requires a BOSH url (httpBindingURL) and the domain name.
Couple of things to check
Make sure the Cisco IM&P XCP Web Connection Manager service on the server is enabled.
The BOSH url port is 7335, and it can be either http, or https. This depends on the security setting on Cisco IM&P. If you checked the "Enable Web Client to CUP Secure Mode" under the system security setting, then the BOSH url will become
https://CUP_SERVER:7335//httpbinding, otherwise, it will be
where CUP_SERVER is the domain of your Cisco IM&P server.