Can Changing the Frequency of a Cellphone Affect a 900MHz Cordless Phone?

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Discussion Overview

The discussion explores the potential interference effects of changing a cellphone's frequency to 900 MHz on a 900 MHz cordless phone. It touches on concepts of frequency hopping, differences between frequency bands, and the implications of frequency and power output regulations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant notes that changing a cellphone to 900 MHz could cause interference with a 900 MHz cordless phone, potentially resulting in echoes or static.
  • Another participant recalls that early cordless phones experienced interference before frequency hopping was implemented, suggesting a similar effect might occur with a cellphone operating at 900 MHz.
  • A participant questions the concept of frequency hopping, seeking clarification on its meaning.
  • Discussion shifts to the differences between 2.4 GHz and 5.8 GHz frequencies, with varying opinions on their impact on range, sound quality, and security.
  • One participant expresses uncertainty about whether 900 MHz phones typically use frequency hopping, suggesting that such features are more common in higher frequency bands.
  • Another participant speculates that GSM technology might scramble signals, implying that an old 900 MHz phone would not interact with a cellphone in a way that causes interference.
  • A question is raised about the relationship between frequency and range, with a participant suggesting that regulatory factors might influence power output at different frequencies.

Areas of Agreement / Disagreement

Participants express differing views on the likelihood and nature of interference between a cellphone and a cordless phone at 900 MHz. There is no consensus on the effects of frequency hopping or the implications of frequency differences on performance.

Contextual Notes

Some claims depend on assumptions about the technology used in cordless phones and cellphones, as well as regulatory factors affecting power output at different frequencies. The discussion does not resolve these complexities.

exequor
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I know that i can change the frequency of a cellphone since afterall most these days are tri-band or quad-band capable. so i was wondering if i changed the frequency to 900mhz what sort of interference i could cause to a 900mhz cordless phone?
 
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in the early days of cordless phones, before frequency hopping was implemented it wasn't all that strange to hear faint echoes of another call when you were talking on your own cordless.

if you were able to get a cell phone to run at 900 MHz (if I'm not mistaken, most of those dual and tri-band phones run at 800/1800 or something like that), then I expect you'd probably get a similar effect.

a lot of cordless phones are digital now, so you might also just get a lot of static.
 
what exactly is frequency hopping?
 
What are the real differences between 2.4 GHz and 5.8 GHz? I've read everything from that 5.8 GHz give you better range, sound quality, and security, to that there's no difference at all, and it is just that the competition in the 2.4 GHz market became so much that they had to open up a new market just so they could charge more.

Specifically, what is meant by 2.4 GHz? What is actually going at that frequency? And how does that effect anything?
 
I'm not so sure that most 900 MHz phones would have frequency hopping. They seem to put those kind of features mostly in the 2.4 or 5.8 GHz phones. The 900 MHz frequency is the most commonly used frequency outside of North America for cell phones, so if you went there (say to Europe) and talked near an old cordless phone then... wait, I still think nothing would happen. I believe GSM technology does something to scramble your signal, and decodes incoming signals before you hear them, and an old 900 MHz phone would not be encoding and decoding its signals, so, like I said, I would guess that still, nothing would happen.
 
hey i thought that the higher the frequency the shorter the wavelength, so why are you getting longer ranges still?
 
Don’t quote me on this but I don't think it is because of electrical qualities but more about the FCC laws concerning different power outputs on specific frequencies. The license may be different at that freq. allowing them to make a more powerful device. It also could just be a gimmick.
 

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