"forbidden" cell phone frequencies

[6079smithw]

I didn't realize how good we had it twenty years ago when I picked up a "modified" scanner from a Craigslist posting and would tune into my neighbors' wireless (wired) home phone conversations whenever I wanted some entertainment. How far we've come in terms of privacy since then . . .

Every now and then I go pearl-diving between 40-50 mHz; believe it or not there's still a few old cordless phones
and baby monitors on those frequencies. I also remember most all of my mid-80's RatShack scanners
being plagued with "cold solder joints" on certain internal jumper wires.
Never was ambitious enuf to bother repairing them...

 

[ArloG]

SDR radios.

 

[GlobalNorth]

Scanner manufactures should really lobby for removal of that legislation to FCC that it no longer serves any purpose and it is anyhow forbidden to try and decode encrypted transmissions.

Enacting law or regulation in the US is comparatively easy. Removing obsolete law or regulation is virtually impossible in comparison to the aforementioned.

Corporations that manufacture scanning receivers lack the substantial financial funding required to influence Congress and or the FCC to act. Both entities are about the imposition of positive liberties via law and regulation, than they are about 'cleaning up' a regulatory relic of the late 1980s.

 

[harbor-tech]

SDR

 

[Mypowerstroke]

Yep, I remember picking up wireless home phones (land line) conversations in the 800Mhz band using an old bearcat hand held scanner with clipped diode.

 

[MTS2000des]

Older UHF TV tuners easily tuned the old 800MHz cellular band, especially those with varactor tuning. I have a 1983 Sharp 13" CRT set with "turret" style VHF tuner and a UHF tuner that goes up to channel 83, and back in the late 1980s, it tuned in the forbidden fruit all day long.

 

[WPXS472]

That law was a knee jerk reaction to a very limited situation. As I remember, some news organizations eavesdropped on some politicians, and got caught doing it. What they did was already illegal. But Congress over reacted and passed an almost useless law. There were already plenty of radios out there that could receive analog cell transmissions, and soon, there were all kinds of work arounds available. It didn't take too long for the cellular companies to go digital, and they will never, ever go back. I remember having a Regency scanner that could manually tune those frequencies, though you couldn't add them to a scan list. My old Icom R7000 worked well there, and I have been told it was a favorite among government agencies. If you wanted to listen up there today, it isn't all that difficult. But, you won't find anything to listen to except digital noise.

 

[MTS2000des]

The "problem" solved itself when the first IS-95 and IS-136 systems (CDMA and TDMA) went online, later GSM, then CDMA2000, UMTS, LTE and now 5G.

At the time though, the cellular industry was exploding. This is also the dawn of the "penny" phones, saturating with subscribers. Remember too, that AMPS/NAMPS was also a haven for fraudsters. Remember seeing folks with "sniffers" near freeways in ATL scanning for fresh ESN/MIN pairs to toss into their Oki 900s to sell to dope boys for two grand a pop.

 

[WPXS472]

Oh yes, and there were special phones that would sniff out ESN/MIN pairs, use them for a couple of calls, and get new ones for you. Never had one, or actually saw one. Things have gotten a lot more secure of late. I am sure there are ways of hacking networks today, but I don't hear about it at all. Must be like the guy who figured out how to hack Motorola Flash codes. He isn't talking about it.

 

[MTS2000des]

Loose lips always sink ships.

But those "golden days" of cellular were interesting, unless your name was Kevin Mitnick.

 

[Randyk4661]

I much preferred the older mobile telephones on VHF and the UHF bands. The low band cordless phone were good too.. I could listen in to the neighbor that would always call the city to complain about the other neighbors. There weren't many handheld cell phones back in the day so they were always changing. I did like to listen Saturday and Sunday mornings, the boyfriends would call the girlfriends and apologize for the night before.

 

[WPXS472]

I was never all that big on listening to cell calls. I did hear a few doozies, however. After having worked in a telephone central office for a few years, I realized that the vast majority of phone calls are just boring.

 

[6079smithw]

Older UHF TV tuners easily tuned the old 800MHz cellular band, especially those with varactor tuning. I have a 1983 Sharp 13" CRT set with "turret" style VHF tuner and a UHF tuner that goes up to channel 83, and back in the late 1980s, it tuned in the forbidden fruit all day long.

Had one of those mid-50s UHF 'converter' boxes by Regency with a manual dial tuner. Looked like a table radio and
would down-convert to VHF Channel 6. Connected it to a standard FM radio tuned to 87.5 mHz and evesdropped away.

 

[6079smithw]

Enacting law or regulation in the US is comparatively easy. Removing obsolete law or regulation is virtually impossible in comparison to the aforementioned.

Agreed! Remember how long it took to finally be rid of that ridiculous 55 MPH speed limt from the 1970s?

 

[Mophead]

I much preferred the older mobile telephones on VHF and the UHF bands. The low band cordless phone were good too.. I could listen in to the neighbor that would always call the city to complain about the other neighbors. There weren't many handheld cell phones back in the day so they were always changing. I did like to listen Saturday and Sunday mornings, the boyfriends would call the girlfriends and apologize for the night before.

Back in the 80's when some cordless phones used a split 1.6 mhz and 49 mhz I found my brother in law talking to his girlfriend. Needless to say I helped my sister dump that loser.

 

[Golay]

Scanner manufactures should really lobby for removal of that legislation to FCC that it no longer serves any purpose and it is anyhow forbidden to try and decode encrypted transmissions. The FCC as government RF experts could then present facts and appeal to the Congress. It creates additional costs to scanner manufactures to add frequency blocking software code and to block hardware hacks by pouring epoxy on circuits that then cannot be repaired in an easy way. It would then be one model with one universal firmware manufactured to cover both US, Europe and Pacific markets.

Not a bad idea.
I believe this law is the reason I can't monitor the 900 MHz ham band on my Yeasu VX-5R.

 

[redbeard]

Not a bad idea.
I believe this law is the reason I can't monitor the 900 MHz ham band on my Yeasu VX-5R.

The law only involves blocking two specific ranges in 800MHz, not 900.

 

[redbeard]

Two others above mentioned SDRs, a $20 USB SDR stick will listen to that range just fine but it's all digital noise. Unless you use software like LTE-Cell-Scanner GitHub - JiaoXianjun/LTE-Cell-Scanner: OpenCL, SDR, TDD/FDD LTE cell scanner, full stack from A/D samples to SIB ASN1 messages decoded in PDSCH, (optimized for RTL-SDR HACKRF and BladeRF board) to decode some technical information. No voice monitoring though.

 

[mmckenna]

As others have said (and I said above), there is nothing for a consumer scanner/receiver to listen to on these bands. Putting the effort into getting the feds to remove this law would be a waste of time.

This is 700MHz LTE band, but it is similar on 800. It's not individual channels, it's just one big wideband signal that your scanner/SDR isn't going to do anything with.



If you really want to know what you are missing, get the $20 SDR mentioned above and listen to the annoying buzz. Or, save 20 bucks and just shove an electric toothbrush in your ear and get the same effect.

There are better things to waste time on.

 

[KB2GOM]

As others have said (and I said above), there is nothing for a consumer scanner/receiver to listen to on these bands. Putting the effort into getting the feds to remove this law would be a waste of time.

This is 700MHz LTE band, but it is similar on 800. It's not individual channels, it's just one big wideband signal that your scanner/SDR isn't going to do anything with.



If you really want to know what you are missing, get the $20 SDR mentioned above and listen to the annoying buzz. Or, save 20 bucks and just shove an electric toothbrush in your ear and get the same effect.

There are better things to waste time on.

"Or, save 20 bucks and just shove an electric toothbrush in your ear and get the same effect." -- that belongs in a Johnny Carson routine on "how to get high without using drugs."

He actually did a bit like that, and my favorite among the suggestions was "put a scoop of Alpo in each armpit and spend the night with a Great Dane."

BTW, I still have an Icom 2SRA that never was blocked. (Still works, too.)

Thanks for the chuckle!