During the past decade the rise of mobile phone use has risen exponentially. With that so has the processing power of these devices.
As the processing abilities of the handset increase so does the need for storage, which in turn means more user data being stored to the associated device. Today's modern Mobile devices contain a whole wealth of forensically valuable data.

A mobile phone handset is made up of many components and data holding areas. A handset is basically a device which supports two way radio communications over mobile phone (cellular) networks of base stations known as cell-sites:
See Sytech - Cell-Site Analysis


The Forensic Analysis of a Mobile Phone Handset for evidentiary value can include the Device, SIM (Subscriber Identity Module) & any attached or associated Memory Cards.



A whole host of information can be recovered from these devices through various Digital Forensic Techniques.
These can include but are not limited to:

General device information and settings
Phone Information
Call Logs
Text Messages (SMS - Short Message Service)
Picture Messages (MMS - Multimedia Messaging Service)
Contacts with Photos
Custom phonebook field labels
Calendar
Notes
Tasks
Pictures & Images
Camera Recordings (Still & Video)
Audio Recordings
Music
Video
Email
Web History
Bookmarks
Cookies
YouTube
Internet Data
Applications
Google Maps
Google Talk
Voicemail
Passwords
User Settings
User Property Lists
Speed Dials
GPS (Locations & Satellite Navigation)
File System Data
3rd party applications settings
Office Documents
WIFI
Paired Wi-Fi networks list with their geo position
Paired Bluetooth devices list
Skype calls, chats and SMS messages history
Skype address book
User dictionary