From Forum Nokia Wiki

ID	KIS000356	Creation date	July 7, 2006
Platform	S60 3rd Edition	Devices	Nokia E60 (sw 1.0610.02.15), Nokia E61 (sw 1.0610.04.04), and Nokia E70 (sw 1.0610.05.06)
Category		Subcategory

Keywords (APIs, classes, methods, functions):

Overview

Large amount of Phonebook entries causes performance problems with VoIP calls

Description

The UI of the device may freeze for an indefinite amount of time when originating or receiving VoIP calls. This defect may occur if the Phonebook of the device has a massive amount of entries.
Currently there is no workaround for this defect.
This defect is can be reproduced with the following devices/software versions: Nokia E60 (sw 1.0610.02.15), Nokia E61 (sw 1.0610.04.04), and Nokia E70 (sw 1.0610.05.06).