I am searching for a tool (or maybe there's a workaround to get it accessed via default tools?) which would let me mount S60 (symbian) filesystems. So far I've found P3nfs, although it seems a bit outdated for current ubuntu (problems with some of gcc modules) or am I doing something in a wrong manner? Thank you in advance
The situation with Nokia phones on Linux is a rather tricky one. I know first hand because I've been a loyal Nokia user for some years now. Unfortunately I've never had a Symbian phone myself, though my brother has had two so far.
What I can tell you is first that it is unlikely you will get good results with the 3rd party software that is available. If you can connect to your device via bluetooth or USB, you maybe able to use Wammu for some limited functionality.
I say limited because you probably won't get access to the actual File System. Gnokii may give you a better deal, but it uses the same backend.
Virtual Machine Method.
There is also the option of using a virtual machine with Ovi Suite. I tried this recently and I can confirm that it works, but you won't be able to update the phone (at least I was not able to). That is because the USB id of the phone changes when you run an update, and it might not reconnect correctly, so to avoid any risk, do not attempt to update the phone using this method!
If you only want to backup contacts and such, then this is your best option.
What you need:
* I will update this answer with more details later, but you should be able to connect to your phone with Ovi Suite and do most tasks (except updating).