If you are trying to use the GET method to send an SMS and you get the "Error: 

error | 1009 | invalid key in query params. | 0 "error, please make sure that you are using all the parameters in the right amount and in the right order.

API input format should be: 

Parameters For MD5: 

One of the reasons behind this error is the wrong HashKey. You can use the below link to generate the hashkey: