Is there a site that I could text a cellphone in australia from?

Without paying, no.

how about pay ones? is there a reliable pay one?

Maybe it can be done. Do you know the service provider in Australia? google SMS to “name of phone service provider” Poke around their site. You may find a free way to send it.

Optus thank you @UScitizen

Most cell carriers (in the US) allow you to email a phone.
How to send email to a phone

I couldn’t Google up anything specific to Australia.

Most cell carriers (in the US) allow you to email a phone.
How to send email to a phone

This looks like maybe a Telstra customer can do that , somebody is giving their email address like 61400000000@mobilenet.telstra.net (the zeros are place holders for the person’s actual phone number).

thanks..trying it

The best site I know of for this kind of information (and it’s very comprehensive) is this one.

@jaytkay, unfortunately, part of the link that you provided is dated. “Teleflip” used to be a phenomenal service to do exactly what the OP requested, and very simply (you didn’t have to know the recipient’s service provider), but they quit offering that some time ago. (I don’t think they ever found a way to make the thing pay for itself.)

Shouldnt skype be more than capable of this, at a very cheap rate too i believe? ..I dont use skype often, but i know it certainly has pc to phone sms functions (im australian and sure it allows it to australian mobile phones)

Most sites that offer pc to phone txt dont work from what i have seen, as i believe the carriers block out most of these.