I find that 3.1 SIP VoIP support N97, and I got a SIP_VoIP_3_x_Settings_v2_0_en.sis and installed on my N97. But it crashes Net settings when start "Advanced VoIP settings". Is there a specific 3.1 version for N97? or N97 is not really supported?
What's going on with N97 SIP VoIP?
VoIP support in Nokia devices: