Today, I have mailed my N900 with the call volume drop issue to the Nokia service center in Huntsville, Alabama. I will update you on how this will turn out.

Also, I would like to know how many people from the United States have this issue? Please post a reply if you're experiencing call volume drop and are in the USA.

I was told by nokia there was corrupt software on my n900. I guess by that they meant up-to-date firmware. They reflashed my n900 back to PR 1.1 (2.2009-51-1) and everything is working fine. I will re-update to PR 1.1.1 and see how things fare....

update
After installing PR 1.1.1 (3.2010.02-8) the issue seems to have been corrected. There was a two second period where the caller and I couldn't hear each other after I changed the volume, but I'm not sure if it was just coencidence or not. For now, I am going to say that the issue has been resolved.

to clarify
the issue was resolved after receiving my unit back from nokia's repair center. The above update was included to highlight the fact that firmware didn't seem to have an effect on this issue (in my case).

I haven't reflashed anything, but after PR 1.1.1 this problem got solved for me. Haven't noticed any more volume dropping.

So again seems to be divided that for some people it's loose cabling and for others software?

I take that back. A few hours later and the problem has resurfaced. I love how Nokia customer care really doesn't.

I can confirm this problem too. Got a N900 in December, had no problems before and after the update to PR1.1. However, the problem started to occur after the update to PR1.1.1.

It does not occur when switching to the speaker or using my BT headset.

It's really annoying since the problem occurs almost every time someone calls.

jinx

I took my phone to the Nokia Care Point here in Helsinki two weeks ago, because the phone had become quite unusable due to the frequent volume dropping during the calls. I got the phone back last week and after that it has been working ok - no volume dropping during calls anymore. According to the receipt they had changed the earpiece speaker part of the phone. No reflashing had been done.

This is an UPDATE to my original post on Feb.24th,2010

I have sent my Nokia N900 for call volume dropping issue on February 24th (Nokia's Huntsville, Alabama repair center) and got the following e-mail from Nokia support today:

"Your device, serial number356938030297..., has been updated with the following status:

A replacement Nokia N900 device, serial number 35693803106...., has been shipped for your original Nokia N900 device, serial number 35693803029...., under Nokia's replacement program. Your device was shipped via shipping vendor on Tue Mar 02 00:00:00 GMT 2010.

Thank you very much for being a valued Nokia Customer!"

I didn't think they would replace my N900 and didn't save my images and music( If you send your phone for repair - always make sure you back up your data.

UPDATE:

Got my phone today. I have updated my new N900 to the latest firmware and so far the call volume during calls has been perfect. I'm keeping my fingers crossed

I have called Nokia again, this time demanding a replacement phone after already having sent in my N900 oncde and receiving it in the same condition that I sent it in + reflashed.(Did this Friday). They escalated the issue and stated they would have someone contact me within 48 business hours.

i have now also tested to press my phone near speaker when talking, and so far it seems to help. Have to test some more though.

its definitely related to harware issue at the "earspeaker" it really helps when you push device from both sides from the corner where led is. im taking my phone to nokia care after easter lets see what they can do it.

I've started having same issue recently and initially I've been inclined to believe it's a software-related issue (happening on both PR1.1 and PR1.1.1), however reading this thread and #6063 entry in bugzilla, I'm getting into hardware-related mood, unfortunately. I just did couple of quick tests, by making a call and pressing device hardly against my ear, which invoked crackling noise and volume fading up/down. Not good. :|

I will try to visit Nokia service centre at Oxford St. in CPW store in London sometime this week asking them to try make a fix on the spot, using instructions from the other thread, but frankly I doubt they'll do it (I've already had not very nice experience with them in regards to my E71 repair). On the other hand, I might try to do the fix myself, however I'm not sure whether I'm that adventurous. ;)

All in all, it seems to be hw-related bug, unfortunately... :(

UPDATE:
Got earpiece in my N900 replaced under warranty moments ago - so far so good, there's no crackling sound when pressing phone against my ear, which is promising. However, I'd need to wait a bit longer and use phone more to see whether fading out volume issue is totally gone.