If you are unable to receive SMS OTP on your registered mobile phone, then maybe your mobile network is unstable or weak. Please check whether you are receiving SMSes from other service providers.
Please follow these simple steps to sort the issue.
1. In case you are using mobile data, turn ON and OFF the airplane mode on your phone.
2. Update your CoinSwitch mobile app to its latest version on Play Store/App Store.
3. Uninstall and reinstall your CoinSwitch mobile app.
Note: For security reasons, in a span of 12 hours, you can generate a maximum of 6 OTPs. If you've exceeded this limit, you will be unable to generate a new OTP for 12 hours.