Hmm.. Nokia Messaging has nothing to do with SIP, chatting or such things. At least when I used to use it (2008-2011) it was Nokia's push e-mail solution, which actually worked wonderfully on my E75 as well as on my N900.

I stopped using it because I found even better solutions:
for Nokia E75: Profimail (best ever mobile e-mail client)
for Nokia N900: mbsync, dovecot and alpine

@Wasmachinemann-NL,
What exactly do you need?