Improved Mobile Telephone Service
Improved Mobile Telephone Service (internal link) may be gone from the public switched telephone network but the system may still be working in private use. Are they any scanner buffs in the midwest who could tell us more? A reader reports:
Hi Tom,
Somewhere in Northwest Illinois, or possibly SE Iowa, an IMTS system is still operating. I have heard it. I haven't had enough time to find which city, although I have a few suspects. I think it is only used by the local telephone company for their own use.
IMTS is the only system that I've run into that marks the next/signalling channel with a 2000 cycle tone. That's what I heard. I did jump to the IMTS conclusion on my own, but it sure seems plausible.
I have run into a scanner buff closer to that area, he has said he was able to hear it and will check it out when he's travelling in near there. He knows IMTS, said he built a circuit to squelch his receiver when the 2000 was on.
I'll let you know if I find anything else.
Al Hajny, P.E.
WB9LIV
Milwaukee WI