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 :)