In article ,
Steve wrote:
When you dial a phone number that's long distance but you don't dial 1
first, you get that really obnoxious high-pitched squeal before
getting the recording. It's been that way forever. Why is that
squealing sound necessary?

Probably a large dose of "thats the way we have always done it".

Its actually 3 tones. I don't recall the frequencies or durations,
google could probably find them for you. Its called SIT (Special
Information Tones) and its used by automatic callers to know they have
reached a bad number.

--
Rich Greenberg N Ft Myers, FL, USA richgr atsign panix.com + 1 239 543 1353
Eastern time. N6LRT I speak for myself & my dogs only. VM'er since CP-67
Canines:Val, Red, Shasta & Casey (RIP), Red & Zero, Siberians Owner:Chinook-L
Retired at the beach Asst Owner:Sibernet-L