You can send  your messages as SMS, to do that you have two options

1- Use a GSM modem to send SMS to mobile  phones, this only works for small number of messages
2-Use a SMPP link to telecom message  center and send bulk SMS

Former is cheaper and rudimentary however later is more sophisticated and expensive

Infrastructure is important, not the implementation.

example below shows you how to do this (you might only be interested in the second part of this article)

www.javaworld.com/.../jw-0417-push_p.html

these guys also have another solution (using both JavaMail and their own SDK)www.simplewire.com/.../010428.html

but if you are doing this through a NMC (OAM) application  and if the network is a cellular GSM based network, you can let SMSC to do this for you through NMC

the first one is usable by regular people
while the latter is through OAM it is only accessible by the network operator - like they are not regular :)

You need to send  your information through WAP gateway in WML format. It's a very simple procedure to do it in your web application.

Please have a look at this page:

developers.sun.com/.../

In order to test your application  you can refer to Nokia web site and download its WAP Gateway simulator and test your application through this simulator.