Much like a Faraday cage is an enclosure made of conductive materials which serves to prevent electrical charges on the outside from frying things on the inside, a Teraport Cage is similar in principle, in that it mitigates the effect of Teraport Area-Denial (TAD) fields within the cage, allowing reasonably safe teraporting from within the cage to any point outside an unfriendly TAD field 2007-01-28.
In strip 2004-10-07 a teraport cage is deployed disguised as a police call box paying tribute to Dr. Who. On 2012-02-02, a variation called the "Beach-Head" cage was introduced. It is an open-front cage designed for rapid deployment and evac.
First mention in the strip: 2004-10-07 (I think - might need this verified).
Other notable appearances
[Insert uncertain and speculative facts about the technology. Include links to Schlock in the Real World where appropriate.]