Overview Of Wap Push; Overview Of Sms - Kannel WAP and SMS gateway User Manual

Chapter 1. Introduction
instance, when it must send a mail notification or a stock quote. For this purpose Wapforum defined
WAP Push.
Push is an application level service, sitting on the top of existing WAP stack. It defines two protocols,
OTA and PAP. OTA is a ligthweigth protocol speaking with WAP stack (to be more specific, with WSP),
PAP speaks with the push initiator. It defines three kind of XML documents, one for the push data itself
and another for protocol purposes (these are called pap document or push control documents).
The server does not simply send push content to the phone, the user would surely not accept, for
instance, interrupting of a voice call. Instead it sends a specific XML document, either Service Indication
or Service Loading. These inform the user about the content becomed available, and it is displayed only
when it is not interrupting anything. It contains an URL specifying the service and a text for user
describing the content. Then the user can decide does he accept push or not.
The push content is sended to the phones over SMS, but the content is fetched by the phone over IP
bearer, for instance CSD or GPRS. Because Push Proxy Gateway tokenises SI and SL documents, it may
fit one SMS message (if not, it is segmented for transfer).
Using two bearers seems to be an unnecessary complication. But quite simply, phones currently operate
this way. Push over GPRS can only simplify matters.

Overview of SMS

SMS, short messaging service, is a way to send short (160 character) messages from one GSM phone to
another. It can also be used to send operator logos, ringing tones, business cards and phone
configurations.
SMS services are content services initiated by SMS message to certain (usually short) phone number,
which then answers with requested content, if available.
When SMS services are used, the client (mobile terminal) sends an SMS message to certain number,
usually a very short specialized number, which points to specific SMS center responsible for that number
(plus possibly many others). This SMS center then sends the message onward to specified receiver in
intra- or Internet, using an SMS center specific protocol. For example, a Nokia SMS center uses CIMD
protocol.
As practically every different kind of SMS center uses different protocol, an SMS gateway is used to
handle connections with SMS centers and to relay them onward in an unified form.
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