I was in my basement, trying to remove the mess of wires, and putting
> them all on a punchdown block. I noticet two old grey bell co wires
> going to a box called an isolation filter. From there they went into a
> box called an "R-tec STU-7". > -Telephone must be wired for briged ringing
> -Use straight line ringers only with bias spring at minimum setting.
> The box is grey, says "Phone Co Property" and is about 9'' by 5'' by > 2'' deep.
> What is this, and what does/did it do (it was disconected)
> Thanks,
> Warren
Warren,
It's an "AML" box, which was used to provide additional dial tone to a house that didn't have an extra pair available on the pole.
Asynchronous Multi-Line units use Frequency Division Multiplexing to allow super-audible transmission of additional dial-tones, the same way DSL uses super-audible frequencies to transmit data. They were powered by a battery which was, in turn, trickle-charged by "bleeding" the POTS line's 48 volts, and each required a matching unit in the CO.
AML units were pressed into service as a short-term solution during the early days of the Internet explosion, when demand for extra dial tones outstripped available plant. They tended to create more problems than they solved, since users complained that dial tone delivered via AML wouldn't work with the new, higher speed modems that also flooded the market in the same time frame.
Ma Bell eventually abandoned them in most areas, prefering instead to build new capacity. They're still available in the secondary market.
HTH.
William
(Filter noise from my address for direct replies)