Connecting to unknown device

Hi, I am pretty new to xbee and digi. Not quite sure if I have the right category either. I have a connectPort x2 and am trying to connect to another radio device. It is not digi, and I do not know the channel/ PAN ID for this device. There are actually two devices, a remote and the system, that communicate by radio. There is little to no documentation for this device. So how might I find the correct channel? I have tried broadcasting, but I am unsure if I had the right channel for that either. I am trying to use XCTU for this. Thanks for the responses.

The following might be helpful when attempting to join 3rd party devices:

http://knowledge.digi.com/articles/Knowledge_Base_Article/Is-my-third-party-RF-radio-compatible-with-Digi-XBee-modules/?q=ZS+third+party

Also, you might want to make sure the SC setting is configured to scan all channels (i.e. 0xffff).