The SMS.to platform comes with an HLR Verification API product  that allows you to verify the mobile numbers to ensure that they are still valid and working. This will help you minimize cost and avoid sending SMS to invalid or inactive mobile numbers. 

HLR Lookup is a real-time query on subscriber information stored in a mobile network operator's Home Location Register (HLR). An HLR is a database with status and context information about every mobile phone number in a mobile network and acts as a register/backbone of subscriber data.

1. Login to your SMS.to account. 

2. In the left side panel, click HLR Number Lookup under Other Tools. 

3. There are several options to check if a phone number is still valid. 

    a. You can copy and paste a single number.

    b. You can also copy and paste multiple numbers. 

Note: Ensure to include the country code when copying and pasting the mobile numbers. 

    c. There is also an option to select mobile numbers from an existing list. 

4. Once you're done entering the number or selecting a list, click the Verify Numbers button on the right side. A confirmation message will be displayed on the upper right side of the window. 

5. The verification process will run several minutes depending on how many mobile numbers you're going to verify. 

In any case, please make sure to provide numbers in the full international format or to configure a default country prefix in your settings. Otherwise there will be no way of knowing which country those numbers are supposed to belong to and they will be returned as invalid. 

You can also use the Default Prefix setting on your account to facilitate this further.

Learn how to check the reports after verifying the numbers here. 

The HLR feature to verify phone numbers is available via API as well.

HLR might not be available in all countries. Kindly test it for the countries you are interested in and get in touch with us if additional countries are required.

If you have any questions, please send an email to support@sms.to