To send an SMS you need to execute the following command: 

$ curl "https://seememobile.com/gateway?key=c2415537c8fca33feab37f0017faddf1fe5a&message=This%20is%20my%20SMS&number=36201234567&callback=4,6,7&format=json"

By executing this command an SMS with the content "This is my SMS" will be sent to 36201234567, response will be in JSON format; and the following status updates will be received in Callbacks 4: "Received by Remote SMSC", 6: "Delivered", és 7: "Undeliverable".

You will receive the following response: 

{"result":"OK","price":14,"code":0,"message":"Your message has been successfully received by the Gateway.","charset":"GSM-7","split":1,"length":5}

More details:

• SMS Gateway Parameters
• SMS Gateway Callback
• Login and check your SMS Gateway settings to request an API Key.