https://www.c-sharpcorner.com/UploadFile/e881fb/send-sms-using-gsm-modem-with-C-Sharp/
Etiqueta: sms
Enviar SMS por NEXMO
http://dotnet-snippets.com/snippet/send-sms/658
Proveedores envio SMS por internet
https://www.twilio.com
http://www.netelip.com/
https://www.nexmo.com/