try odoo twilio /  Plivo SMS   By webkul

Here is the Module Link:

https://store.webkul.com/Odoo/Communication.html

https://www.odoo.com/apps/modules/8.0/plivo_gateway/

Hello Mr.Undan

Find following links that will help you

1.https://www.odoo.com/apps/modules/9.0/sms_frame/

2.https://www.odoo.com/apps/modules/9.0/sms_gateway/

You can also write python code to send sms for example

first you have to register or buy the twilio gateway get account_sid and token

from twilio.rest import TwilioRestClient

account_sid = "your sid"

auth_token = "your_token"

client = TwilioRestClient(account_sid, auth_token)

message = client.messages.create(to="reciever_no", from_="+sender_no",body="Hello there!")