The Videotex could run in an offline mode. It lets you enter pages of text and it was possible to later upload that data to an online service. To experience this, run trs80gp -mv or use File → Change Model → Videotex. Press almost any key (except escape) and you'll be entering text in the offline mode. Take time to be amazed that it word-wraps text as you type.
If you press escape (which is the emulated BREAK key) it will then prompt you with "PLACE CALL". On the real machine you'd pick up your phone, dial the information service. When in answered you'd put the phone down and press ENTER to let it know you're connected.
When you hung up the phone (or the server hung up) the terminal will
print OFF LINE indicating this. There was also an LED, I gather.
There must be some way to proceed from this point but either I don't
know what it is or trs80gp doesn't quite emulate it yet. You can reset
the emulator if necessary.
You may find the
Videotex manual and technical documentation helpful. It does support
a monochrome 128 x 96 graphics mode. And there was even a way to download
6809 code. At which point trs80gp's built-in 6809 debugger may come in handy.