While Windows Phone contains many new features, a number of capabilities and certain programs that were a part of previous versions up to Windows Mobile 6.5 were removed or changed. Until Windows Mobile 6.5, the previous version did always cover the complete feature range of the predecessor version.
The following is a list of features which were present in Windows Mobile 6.5 but were removed in Windows Phone 7.0.
Calling
The list of past phone calls is now a single list, and cannot be separated into inbound, outbound or missed calls
Sync
Windows Phone does not support USB sync with Microsoft Outlook's Calendar, Contacts, Tasks and Notes as opposed to older versions of Windows Mobile with Desktop ActiveSync. Syncing Contacts and Appointments is done via cloud-based services (Windows Live, Google, or Exchange Server), and no method to sync this information directly with a PC is provided. Third-party software, such as Akruto Sync, provides some of this functionality. A petition to Microsoft was filed to reinstate USB sync for Outlook.
Other
Adobe Flash
Ability to open .exe files (desktop Windows executeables), such as 7-Zip 32-bit for desktop.
Features subsequently implemented in Windows Phone 7.5
Internet sockets
Cut, copy, and paste
Partial multitasking for 3rd party apps
Connecting to Wi-Fi (wireless) access points with hidden SSID, but without WPA
Tethering to a computer
Custom ringtones
Universal email inbox
USSD messages
VoIP calling through a separate app
Features subsequently implemented in Windows Phone 8.0
Removable SD cards
USB mass-storage
Bluetooth file transfers
Connecting to Wi-Fi (wireless) access points with both a hidden SSID and WPA protection Sideloading for corporate apps VoIP and IP Videocalling integrated in the Phone app Support for Office documents with security permissions On-device encryption Strong passwords Full Exchange support Native applications Full background multitasking
Features subsequently implemented in Windows Phone 8.1
IPsec security (VPN) System-wide file manager The 'Weekly' view in the Calendar app Universal search UMTS/LTE Videocalling