old phone phreakers: can anyone tell me exactly what a Watts extender (number) is?

unbelievably, web searches provide near zero results. even usenet has next to nothing.

i saw it referred to *many* times over the years in hacker/phreaker books and articles, but never came across a technical description of how one worked.

by context, its purpose is to extend one's local calling range to long distance without paying for it, but i've never seen an explanation of how it worked.

#telecom #phreaking #hacking