Cell Phone Interference - Ferrite Beads Help ?

[tsgcisco]

We have a few hundred 7940 and 7960 phones and users (including myself) constantly experience interference through the phones speaker when they are not on the phone. I have noticed that when my phone switches it seems among towers or signals it does this, as well as right before a text message or phone call. Its funny because I can usually tell when my phone is about to ring or when I get a text message before my cell phone notifies me.

I am wondering if ferrite beads might help, but not sure. Just wondering if anyone else has experienced this?

[ttheado]

I have also experience this, and it is very annoying. I have told users to move the device further from the data cable and phone.

I am open to other ideas.

[carijit]

This is a known problem with some batch of Cisco phones.

Cisco is aware of the problem and is shipping phones with improved resistance to interference.

So either you have to scrap your old phones with newer ones or ask your AM for some credit back for these faulty phones

[tvanblon]

These 2 links on Cisco's site document the interference issue you have experienced:

http://www.cisco.com/en/US/customer/products/hw/phones/ps379/products_user_guide_chapter09186a008008117c.html

"Using a cell, mobile, or GSM phone, or two-way radio in close proximity to a Cisco IP Phone might cause interference. For more information, refer to the manufacturer's documentation of the interfering device."

http://www.cisco.com/en/US/customer/products/hw/phones/ps379/products_administration_guide_chapter09186a008012922c.html#wp1051945

"Using a cell phone or mobile phone in close proximity to a Cisco IP Phone might cause interference with the speakerphone on your Cisco IP Phone. "

There is also a documented bug, the ID is CSCdt97519, and it reads:

SYMPTOM:

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When a mobile phone is being used near to an IP phone, 7960, there is inference heard through the speaker of the IP phone, this is something that is heard at a low level on other traditional speaker phones but it is loud on the IP phone.

CONDITIONS:

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- Mobile phone is near from the 7960 IP phone.

- Mobile phone it''s looking for a BTS or it''s renegotiating the BTS connection or before it gets a new call.

- It''s noticeable when a live call is on the IP phone using handset or hands-free.

- Always it''s reproducible at customer side.

- The mobiles are connected to the BT Cell Net.

- Phone revision number: 68-0808-04 Rev.60

WORKAROUND:

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To move the GSM phone from the IP phone at least 30 cm

Note: The customer asks for a product enhancement to eliminate this interference.

-Tim