Every time you install software to devices using the DME web interface, a message such as this:
asks you to choose if you want to install on new devices or existing devices. This distinction is especially important if you are using OMA DM for installing the DME client on the devices:
New devices are devices that are not known to the DME system at all - that is, they have never been connected using OMA DM or the DME protocol to the DME server. They are identified by their phone number. In principle, you do not know which phone model is at the receiving end of the installation prompt. Therefore, if you are installing the DME client using OMA DM, it is a good choice to do so by bootstrapping the device from the Devices tab and including the DME client, instead of picking a DME client first and then ordering an installation. This way, the DM bootstrap mechanism is allowed to select the default DME client for the platform in question. See Bootstrap devices for more information.
Existing devices are devices that are known to the DME system. Some version of the DME client has already been installed, and they have reported their characteristics and properties to the DME server. When installing the DME client using OMA DM, DME shows you a list of devices in the system to which the selected DME client applies (for instance Symbian S60 devices if you chose to install the S60 client). You can then choose the specific devices to which you want to install the client.