I would like to know how to send a sms (text message) from windows application to a mobile phone (with entering the number) - for free.
One and the only option I know (and I tried) is to send it using email.
But I do not have any provider in my country to support this future. So the only thing that I am left with is to pay a service, like www.smsmail.com.

Does anyone have any idea of sometihng else how to send sms from pc (windows, windows application)?

There is no way to just send a sms message. You need a gateway. Some providers like at&t provide a email gateway for free use ##########@txt.att.net (i think this is right) but it only works for at&t phones. In order to send a sms you must be part of the phone network. a sms message is a "push" message that is relayed to the phone when the phone is communicating with the cell tower maintaining service, not during calls or using the net. So somewhere there needs to be a device on a phone network relaying your programs messages to the phone network. And Phone companies don't just give away texting rights. It costs me 30 bucks a month just to use it on my phone. i would expect to pay hundreds to use it in a commercial setting from software.

So your options are to subscribe to a sms gateway and use its api to send messages. or get a GMS modem and pay for GSM modem phone service and interact with it to send SMS. (essentially automating a phone with your computer)

best of luck though.

or SMS provider, which provides you with web service or so to call it to send SMS...