Question about AT&T 5840 5.8GHz Speakerphone/Answering/Caller ID Answering Machine

1 Answer

ATT 5840 answering machine

Had a power outage last week and now nothing about the answering machine will work.  It clicks and flashes the numbers "88" every second.  I tried to reset and even disconnected from the wall.

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 47 Answers
Re: ATT 5840 answering machine

You need to reset the cordless phone. This sounds like a lightning strike , if it was the phone is finished. Unplug it , wait 20 seconds and plug it back in again.

Posted on May 11, 2008

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

1 Answer

I can't find my manual. The power went out and when it came back on my machine now beeps incessantly and flashes an F2. Don't know what that stands for or how to stop the beeping. Unplugged and plugged...

Well I feel your pain. I have the same machine and we had a winter storm about 3 weeks ago and had a power outage too. When I went to reset my answering machine it shows a F0 code which I can't find out what it means either. I also have tried everything, nothing works, none of the buttons respond and all i get is the F0 error code and constant beeping. I am still trying desperately to find a cure for this. Like you I'm afraid the power surge fried something. The manual gave one number which is 1-800-222-3111, I called and they couldn't help me because this was an old discontinued model. Grrrr...
I can give you the web site to get a copy of your manual that you can print or read:

If you find a cure for this please post it. I love this machine and think it is so much better than most of whats out there. I don't want to have to replace it but need to do something soon. Good luck, Barb

Feb 24, 2011 | AT&T 1725 Answering Machine

3 Answers

AT&T 5840 5.8GHz

try reseting the phone by unpluging it and also removeing the batterys. Il check the manual.

Aug 23, 2008 | AT&T 5840 5.8GHz...

2 Answers

As machine window flashing 88 and clicking

Disconnect power cable and remove battery, it should reset

Jul 18, 2008 | AT&T 5840 5.8GHz...

1 Answer

How do I get the answering machine to work properly?

Answering System Feature Setup
You can set up one feature at a time, or you can set up
a feature and then move on to set up another feature.
1 Make sure the answering system is on.
2 Press and release Uuntil you hear the
system announce the feature you want to set.
Refer to the Feature Summary chart on page 54
for a description of the features and your choices.
3 Press cto hear the feature’s settings.
4 Press Uto move on to the next feature
or press a PLAY/STOP button to exit Feature

You can download the pdf format manual on this website:

Sep 12, 2010 | AT&T 5840 5.8GHz...

1 Answer

My att 5.8digitalbase phone only speaker phone works, How to fix?

If you want the manual, just go to then scroll down to your model 5840 Manual. It will download the manual for you.

Feb 10, 2009 | AT&T 5840 5.8GHz...

1 Answer

How do I change my phone from announcement only mode?

Your question is not clear enough. Change from announcement only mode to ...

There is user manual online

You can check it out ,if you have more question, let me know.

Aug 05, 2008 | AT&T 1717 Digital Answering Machine

1 Answer

ATT 5840

The processor chip that records the voice is a multi level SMD technology chip. The tech who changes it will need the proper soldering facilities for this type of work.

The only people who can service the phone are the authorized service people for ATT. They will not sell parts to non authorized service people, even if they have the proper facilities to change the chip.

For service on your phone, the service center will normaly change the complete circuit board. If the phone is out of warranty, the cost would not be worth it.

Jerry G.

Jul 07, 2008 | AT&T 5840 5.8GHz...

1 Answer

5840 static when answered

change your batteries and realign the base and the handet. poor batteries cause the Txers to drift off frequency

Apr 30, 2008 | AT&T 5840 5.8GHz...

1 Answer

As machine window flashing 88 and clicking

I have same problem how do i fix this

Nov 05, 2007 | AT&T 5840 5.8GHz...

4 Answers

At&t 1739 answering machine

Get remote access code from the machine get it by pressing set up button on answering machine. Go to another phone when machine picks up enter access code then enter *7 record new message press 5 when done then to end call enter *9

Sep 18, 2007 | Answering Machines

Not finding what you are looking for?
AT&T 5840 5.8GHz Speakerphone/Answering/Caller ID Answering Machine Logo

301 people viewed this question

Ask a Question

Usually answered in minutes!

Top AT&T Answering Machines Experts


Level 3 Expert

94113 Answers

Cindy Wells

Level 3 Expert

4722 Answers


Level 3 Expert

18259 Answers

Are you an AT&T Answering Machine Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides