## Subscription Service

The phone provides a set of values such as the IP address and user telephone number to subscription servers when the telephones register with the media server. An explicit subscription message can also be sent to the phone using <Push type=”subscribe”... /> to re-subscribe the phones.

NOTE: See Chapter 3: Creating Push Messages for more details on sending a re-subscribe Push Request to the telephone.

Applications must maintain their own database of information for each phone. Databases can be built with respect to a group of telephones or an individual phone.

A typical example in a corporate work environment is to have distribution lists according to specific teams. An application can only target pushes to that team such as “team meeting reminders” with conference bridge numbers, etc.

Once an application builds a database that has the required information of all of the telephones in the network, it can target Push Content or an audio stream to a specific phone or a group of phones. Additionally, Push Initiator Servers can poll the phone to update its database.

NOTE: A phone in a logoff state does not unsubscribe from the Subscription server.