What is a WAP-Push Message?

A WAP-Push message is a message that is similar to a regular text message, but appears in the Service Inbox (or similar) of the clients phone. It contains a link to a mobile web page, which is then 'drilled down' into by the client, over a WAP, GPRS, or 3G connection.

Why use WAP over MMS?

Per message, WAP messages are more cost effective to send than MMS messages because they do not contain the whole message, and as such bandwidth is greatly reduced.

Compatibility between phones and operators is not as good with MMS as it is with WAP-Push.

There is no way of tracking the MMS to see if the message was read or not (it's fire-and-forget, as opposed to WAP's 'introduction' technology). Therefore no meaningful dialog/tracking can take place.

Images cannot be rendered dynamically using MMS, and as such, it's ability as a real-time technology is limited.