Problem : When somebody call me on my mobile - the N900 start to ring after 3 times of ringing on the callers phone !. Why this ? Please can somebody give me a answr of this ??

I can only think of a couple of reasons:
1. You might have some software installed that is slowing the n900 down to the fact that it can't initiate the call handling sequence fast enough
2. Try using the default ringtone (just in case)
3. Might be a lag in the operator or network

I appreciate English isn't Pipo's first language, but damn Karmiko how did you understand that?

I think my english is not so bad... but it was difficult to explain

I solved the problem with flashing my phone.
(but less some apps)

Pipo!
There are some apps, that cause this, but we don't know which are those. Please watch your ringing time, and start a new thread when an installed app make your phone late.
Thx

I have reflashed the device .. now it's ok. when it comes up again I will post it

I found that if you call an N900 while it's doing some heavy processing (like playing a video) there will be a huge delay before it starts ringing. Other than that, my only guess would be that it could be a delay with the carrier.