[This page is outdated! See instead the wiki page: https://wiki.project-tamriel.com/wiki/Scripting#Enabling_and_disabling_teleportation]
Introduction
Morrowind has two functions to enable or disable teleporting, aptly named EnableTeleporting and DisableTeleporting [UESP Wiki].
These functions disable hard-coded teleportation spells (Divine and Almsivi Intervention, Recall), but can not block scripted teleportation (such as the Vampire amulets players can acquire, or Barilzar's Mazed Band). There is also no way to check if teleporation is disabled.
This is where Tamriel_Data comes in with a teleportation "framework", essentially a single global variable named T_Glob_GetTeleportingDisabled.
General Overview
Ultimately, this is a very simple thing: T_Glob_GetTeleportingDisabled should be run in parallel to EnableTeleporting and DisableTeleporting. Set one where the other is set: 0 when teleporting is enabled and 1 when it is disabled.
Example Implementation
How to set it
This is using an example script disabling teleporting on entering a certain cell.
It is activated by a separate activator script and runs globally until it is shut off once the player leaves the cell.
How to read it
This is an example script heavily cribbed from vanilla scripts - by equipping the amulet of the Draculus Clan, the player is supposed to be teleported back to the clan's lair.
The script will fail silently.