Understanding Mobile Device Connectivity
Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-02-02
A wide variety of mobile devices can synchronize with Microsoft Exchange Server 2007. Most mobile devices that synchronize with Exchange 2007 are cellular telephones. These devices can run operating systems such as Windows Mobile, Symbian, Palm, and Nokia. For an overview of the different mobile devices that are enabled for Exchange ActiveSync, see Understanding Mobile Devices.
Regardless of the type of device that you select, there are two primary ways to connect to Exchange 2007: by using cellular connectivity and by using wireless connectivity. This topic provides an overview of the two connectivity options.
All mobile devices that are enabled for Exchange ActiveSync can use cellular connectivity to synchronize with Exchange 2007. There are several different types of cellular data networks. Regardless of the type of cellular data network that your mobile device uses, the method of synchronization is the same. If the operating system of your device is Windows Mobile 5.0 with the Messaging & Security Feature Pack or Windows Mobile 6.0, synchronization is accomplished through Direct Push. If your device has another operating system, manual synchronization is used. When a device uses Direct Push to synchronize with Exchange 2007, it establishes a long-standing HTTPS connection with the Exchange server. When the connection is first established, the device sets a what is called a heartbeat interval. The default heartbeat interval is 15 minutes. If any new messages are added to monitored folders on the Exchange server within this heartbeat interval, the server informs the device and the device initiates synchronization. When synchronization is complete, a new HTTPS request is initiated and the process is repeated. For more information about Direct Push, see Understanding Direct Push.
Cellular data plans can charge by the minute, by the megabyte, or offer unlimited data transfer. When you use a cellular data connection with Exchange 2007 Direct Push, we recommend purchasing an unlimited data plan.
Many of the mobile devices that are enabled for Exchange ActiveSync can connect to a wireless LAN. Connecting to a wireless LAN can provide faster network speeds and better coverage in areas where cellular coverage is unreliable. In addition, wireless access is sometimes offered at commercial locations such as coffee shops and book stores. The primary disadvantage to using wireless connectivity is that Direct Push will not work over a wireless LAN. Users who connect over a wireless LAN can perform manual synchronizations or configure scheduled synchronizations as frequently as every five minutes.