If settings do not apply, delete the profile from "Advanced VoIP settings" first, then edit the "SIP settings" and re-add the service. Symbian SIP Setup VoIP Settings Configuration - AltoTelecom
SIP VoIP 3.1 Settings — Symbian^3 v1.0 (EN) — Full sip voip 3 1 settings symbian 3 v1 0 en full
To use SIP on Symbian^3, you must ensure the is installed. Unlike older S60v3 devices, Symbian^3 often required this specific SIS file to "unlock" the Advanced VoIP settings menu. If settings do not apply, delete the profile