Hello guys.My English is not very good, but I will do my best to explain the problem.
I have the phone from 4 days.On day one I updated to PR1.2.
Very often during my calls, people's voices crackling.
I test on phone speakers, on headphones and on his normal speaker for calls - no change.
I uninstalled all software and restore it to original settings.
No change.
The only two applications I have are Maemo Pr.1.2 and rootsh.

When I play videos and music - NO CRACKLING.

I guess it has something to do with microphone or calls spearker or I don't know.

I had my phone one time freezed with brrrrrrrrrrrrrrrrr sound, but I restarted it and It was Ok.

Ï must mention the phone somehow break the right speaker of my old Sony headphones.

What is your suggestion?
Any idea how to reflash it to Pr.1.1.1?

have you tried puting in a diffrent network sim card and trying to call ??

because im in the UK and i used to have O2 sim in my n900 and i used to get simialr crackling during making and reciving calls but when i changed to a diffrent network provider (virign) then the crackling disaperaed.

hello brother

you are not alone , iam also facing the same issue very frequently.
it makes a viered sound between a call .

Right.
Interesting but today I made 3 calls - one to homephone, one to my father, and I received call from my mother.Everything was good.
By the way I think my head speaker for phone calls is not very well centred, because when I put the phone on angle (right side is close to my ear (face), left away) I can hear the other person better.
Thank you for the inputs guys

Lots of people have had speaker issues with their N900.

If the probably only happens with the regular speaker and not the loud speaker then your speaker probably needs replacing. Take it to a Nokia repair centre (or replace it yourself if your not worried about the warranty), it's not a hard job...

If it's not the speaker or mic:

Between your handset and the cell station some pretty complex things happen. Your voice is essentially digitized and carved up in to time slices and sent as a bursting transmission (TDMA) - this aspect wont really give you 'crackling' though if you have a high bit error rate then you might end up getting tearing sounds or call dropouts as you lose sync. Similar to the sound you get from your DVD player when you stick in a scratched up CD.

The next part of the equation is getting your voice from the cell tower to the exchange. Maybe some fiber, maybe microwave, maybe both : ) Each of these introduce a little bit of latency, as well as a similar situation to what I described in my paragraph above. Some might even recode your voice for more efficiency on the bearers.

After hitting the exchange it's anyones guess as to where it will go before it reaches your mom on the other end of the connection : )

These days almost the whole system is digital from end to end, so again, no crackling as such, maybe that high pitched squeaky noise as the voice becomes choppy though.

Maybe all of this happens again in reverse if the person you are calling is on a mobile. If it's a traditional land line, then anything from lightning to a hair dryer could be causing the crackling.

It'd be cool if there was an easy answer, darkjoker is absolutely right, some carriers care more than others about this issue. You can't really do much about a poor quality link between your phone and the tower other than repositioning yourself, as for the rest of it, you might have 15 companies all sticking their fingers in the network spaghetti just to call your sister across town.

I had this problem some weeks ago. When I manually switched to 3G it was gone. Switched back to 2G also gone.

But I have another problem. I can hear some noise in the earspeaker during calls.

This is the noise -> http://www.youtube.com/watch?v=23rdefO4gBU

I get that noise in my ear piece too, but not on loudspeaker.

I tested on headphones,earpiece speaker and N900 speakers - crackling presented. Conclusion: All three must be fine.
I guess it is microphone or earpiece speaker (sometimes the voices are very low).

To be honest in the beggining I had my left speaker crackling for while.Now the problem is gone somehow. Oh and my Sony headphones (the right one) was burnd during the tests.But I don't have straight proofs for relationship.

We don't have Nokia Service Centre in my country (may be one in Sofia, but I'm 400 km away).I can ask the girl in the shop for new phone, but everything other looks fine, may be I was stupid and updated to PR.1.2 but It is my fall.
Have a nice day

May be choopy is better word to describe the problem.
Or may be both crackling and choppy.

Yesterday I had phone conversations with the girl from the shop and with friend. I first case her voice was crystal clear, and in second on some moments I can barely hear my friend.

Thanks you to all for your attention