Mobile Phone / Desk phone noise interference - how to prevent?

It is the low frequency circuit in the phone(s), and so far as I know, assuming the phone to be "on", there is no way to solve it except to keep the phone away. You can try new speakers, but that did not solve it for me.

If it is really bothersome, consider moving the client to a laptop with no outboard speakers. I don't have much trouble with my laptop. ... Thinkpads_User

My apologies - misread. Answer of the first part is the same. Keep the mobile away from the land phone. Again, you can try changing the land phone. I have little problem with Northern Telecom phones, but I have still learned to keep my distance with the mobile. .. Thinkpads_User

I will add, the client in question demands the best. He has a specific landline phone that he sourced from scandinivia at expense and so will not change it. He also would not consider changing his PC.

In short he expects to get exactly what he wants, so trying to work aroud this. It does seem to be particuarly bad in that office and I'm hoping the installation of a mobile phone signal booster will aid this (As then the handsets should not throw out so much singal), but I'm open to other suggestions or learning more about what the problem is so I can at least prepare a very good explanation.

but solution will be better.

You cannot modify the mobile phones and the oscillator circuits inside is what is causing it. So there is no solution to the phone. Given the pickiness of your client, ask that they keep the phone out of the way, because changing the land equipment is the only way I know, and even that requires some experimentation. I have lived long with this so it is not new or strange to me. ... Thinkpads_User

The explanation you are looking for is simple.

Mobile phone frequencies use electrical pulses which generate disturbance on any wire in the vicinity. This problem is audible especially when the phone is in use / hand shaking with the mobile cell tower as there is a transmission of in a simple word - power. The energy field being generated in the cellular transmission is being picked up by the desk phone wiring causing the hiss (think of it as a low level fax transmission /modem handshaking sound, if you have heard those recently)

The solution for this is NOT a signal booster, but rather a signal ARRESTOR, Visit any electrical store and ask them for a wire arrestor. They are cheap and you have already seen one connected to many household appliances. Just clip it onto the wire going into the desk phone and it will help to a great extent.

However the only true solution would be to distance the two phones from each other.

RB

This sounds very interesting. Do you have any links t any on a website. I've googled it and so far come with a lot of different results but nothing specifically for what you say. So any example would be a good. A UK supplier would even be better.
Many thanks.

I forgot to give you the jargon guide - the unit you are looking for is a RFI blocker.

RFI = radio frequency interence

Noise control = controlling the effect of RFI on electrical wiring (phone cable included)

Remember not all arresters will look like the one in the link I provided - some look just like a cylindrical object wrapped around your cable - usually seen on laptop power cables as an example.

Hope its clearer ;) Good luck.

RB

It might work. However the noise we here is usually not RF - it is normally a much lower frequency. See what happens. ... Thinkpads_User

@thinkpads_user

Appreciate your feedback. Would like to clarify one thing here, if I may, cell phones do indeed emit RFI and EMI. The frequency of the signal has nothing to do with it. To avoid filling the thread with pointless and unneccessary jargon, I have tried to keep the technical aspects out of my posts while enabling a reasonable explanation to be provided.

A search on Google will provide you with the technical aspects of RFI and EMI caused by cell phones - a simple example being the fact that you are asked to switch off your cell phones and during flight on commercial aircraft.

RB

RohitBagchi

Very interesting stuff. I will trywith a local electrical supplie tomorrow to see what they come up wtih and I might take a wrap of aluminium foil as well.

All very interesting stuff.

Regarding the mobile phone signal booster, the reason why this might help I was thinking is, when the signal is weak as in their office, the mobile phones work harder to get their signal, and therefore throw out more signal which could be making things worse. Once the booster gets installed, the mobiles should be able to pick up a signal more easily, and therefore not through out so much "power" which is picked up by the landline.

any logic there, or nonesense?

Also note, alas I've not found anywhre in the UK that has this stuff or anyone who knows what I'm talking about at this point.

Maybe there is diffeent terminology for it in the UK.

Also I will add the phone in question is an IP phone I believe so it wil be plugged into the floor port via an ethernet cable. So I imagine (I will see it today) there will be a power cable going into it and an ethernet cable.

Hey there again,

I think you may not have completely understood the nature of interference through my less than completely technical posts.

Remember, all electronic devices (phones / ip phones ....) have wiring in the system - usually copper wire. Interference is picked up by this wire and audible through the speakers - remember sound is also transmitted in the same fashion.

I believe you haven't been able to explain the problem to the electrician which is why all the confusion, but tell you what. Here's something inexpensive you can try - take along a roll of tin foil to the phone and just for the sake of experimentation, loosely wrap the telephone in the foil and then use the cellular phone and see if you can see the difference.

RFI and EMI shielding is a VERY common issue, especially in government environments, and the technology is VERY common. Even if you look at the manual for your TV / Microwave, there will usually be a statement of compliance.

For the sake of understanding, give it a shot. If it helps, you know what you need to solve the problem. If it doesn't, well you have atleast gained some new intel.

Cheers.
RB

Just so there is no confusion - the statement :

has been used to cover the appliance from the wall socket, the power socket and the internal wiring and circuitry of the electrical / electronic device.

OK I went to the client and results were interesting. It seems a particular LG deskphone with the culprit. It must have had poor internal sheilding.

I wrapped it in aluminim foil and this did reduce the interference levels. However that particular device was due for replacment anyway and so I swaped it out and problem seems signficanly reduced.
Time will tell when the client returns but at present seems better. So I guess some phones are just not very well sheilded against interference.

Thanks for the very interesting input on this matter.

Not the direct solution for me in this case, but the comments and all comments in this thred were very useful in investigating the problem.

Many thanks to all comments.