Question: My customers are not receiving SMS to verify their OTP. We have integrated Twilio with Parse and is using it for OTP Authentication. We are based out of India. 

We faced this during test account. It never used to send SMS in the night and received all SMS next day morning. Now we are using a paid account and still the same issue i.e. my customer did not get any SMS during night and also not in the morning. Kindly help. 

We will not be able to do business if our customers do not receive OTP SMS. 

Is this a known issue ?

Answer: 
India is difficult to get text messages to, there are lots of rules and restrictions

Completed a project recently using a Twilio competitor (Clickatell) and it was the very same problem.

Frow Twilio's website:

**Are there limitations on sending SMS messages to Indian mobile devices?**

> 
> **3. They are only delivered between the hours of 9 A.M. and 9 P.M. local Indian time**
> 
> 
> If you’ve been seeing delivery delays when sending to Indian numbers,
>  make sure you are making the requests during the operational hours of
>  9 A.M. to 9 P.M., as overnight messages are likely to be cached until
>  the next day.
> 
> 
> 

<https://www.twilio.com/help/faq/sms/are-there-limitations-on-sending-sms-messages-to-indian-mobile-devices>
As E.J. said above, India has a lot of regulations to follow when sending SMS.

This is not a Twilio specific issue.. Other SMS APIs will have the same outcome. 

For example, as stated on Nexmo's Country Specific Rules & Regulations webpage:

"We can only guarantee message delivery between 9am to 9pm. Messages submitted after 9pm ***we will attempt to send***, but due to local regulations, these messages will be queued until the morning and you will be charged for them as usual."

Here is some more in-detailed information: [India: Features & Restrictions](https://help.nexmo.com/hc/en-us/articles/204017423-India-Features-Restrictions)