I just watched this video https://www.youtube.com/watch?v=bwNyBfCk_cw
and there's something that made me wonder. around second 18, he hovers over the portal, and gets a tooltip displayed.
That must mean that there's a 'physical' object to receive mouseover events.
That unconvinced me, that triggers would solely be handled by the server; also because there are so many other things, the client is trusted with, i still think it's possible or maybe just for some portals to be handled clientside too (collision + reporting to server -> answer from server + action initiation)

This is a good travel video:
 
https://youtu.be/vR0mo_rzztQ?list=PLPVQb...1MNyVanQlp

That's interesting. The detection part like "Am I in a SBWorldPortal, if yes, teleport me" is server side, I am pretty sure of that because on the SDK the code involved request the GameServer object. But it does not avoid the possibility to have something clientside too. I don't remember if on the beta we had these tooltips so  may be it's not on the current version we are working on (or maybe it is but we still have to found it!).
 
Edit: Btw I have the confirmation that "Claustroport" means "Teleport inside current map" and "Teleport" means "Teleport to another worldmap".
See SBGame.Content_API the functions ClaustroportPawn and TeleportPawn.
Edit²: The tooltips are actually SBGamePlay.TooltipActor and some have the tag "InteractiveLevelElement...

To test out the claustroport function you can use the tavern or the shops in hawksmouth city.
Near the doors you'll see that the mouse pointer changes and close enough can be right clicked to actualy activate it.
This means a character move inside the map to the correct location for either tavern or shop.
For example the spirit shop door at location -12648, -11709, 7896 will bring you inside the shop at -205090, 2922, 4161.
When using a move position just outside the destination might give you a view through the map so you can look around and see
the other shops / tavern / academy locations.
The only portal in Hawks city that would activate by walking into it was the portal to Aldenvault.
J-W.

Yes that's exactly what I am currently reversing, in fact I just needed to extract automatically spawn locations from the packages that are activated when clicking on a door and now it's done so I think I am not far of a working solution, there is still the packet to reverse and the doc to write but I have hopes to find time. ^^
For the portals the data is also extracted and the process is almost completely understood but there is still a bit of stuff to reverse.

If I remember correctly there is a 'sheet' (I think it was just a static mesh) that has the yellow border effect as a texture, and which displays the tooltip. This sheet didn't have any collision.
When you walked through it, you walked into the radius of a trigger, which then triggered the teleportation.