The reservable Jabber Guest lab does not have Expressway, and can do only on-network stuff. You can still test endpoints by connecting them to the lab via VPN (i.e. Jabber) and you can test the Jabber Guest link management API.
The shared endpoint lab actually does have an external Jabber Guest/Expressway instance attached to it. It is what is used in the Jabber Guest learning lab exercise:
You could register an endpoint to the shared endpoint lab, then make a call to it using the Jabber Guest URL from the exercise, replacing '5555' with the DN assigned to your endpoint:
Thanks very much for the answer. What you said makes sense. Ideally though, I'm looking to register that far end (non Jabber guest) static endpoint to the Lab environment via Expressway (not via VPN).
From what I could tell by setting up a request to the shared endpoint lab, it looks as though all of the endpoints are required to access it over VPN. Is that correct?
True...the shared endpoint lab does not yet support registering endpoints via Expressway (non-VPN) - planned as a future enhancement.
You can accomplish registering non-softphone endpoints (like Cisco deskphones) to the shared endpoint lab by configuring a Cisco AnyConnect VPN capable router with the sandbox VPN details, then plugging the device into the router.
In the "Lab Details" document under the Jabber Guest Sandbox Lab, the following is listed:
This Lab does not Contain Expressway. VPN is required to make calls to the sandbox. If you want to make a Jabber Guest Call to a Static endpoint over Expressway
It seems as though there's something missing from that paragraph. I'm curious if it's possible to make a Jabber Guest Call to a static endpoint over expressway either from this lab or a different one.