You can use the SMS OTP code service to generate and send in SMS a one-time authentication password for his service, specifying the following combinations:

{gen_otp_09,9} – generates a numeric code using values ​​from 0 to 9, 9 characters long
{gen_otp_az, 9} – generate alphabetic code using values ​​from a to z, using only lowercase, 9 characters lon
{gen_otp_aZ, 9} – generate alphabetic code using values ​​from a to z using upper and lower case, 9 characters long
{gen_otp_AZ, 9} – generate alphabetic code using values ​​from a to z using only upper case, 9 characters long
{gen_otp_a9,9} – generate an alphanumeric code using values ​​from a to 9 using upper and lower case, 9 characters long
{gen_otp _ **, 9} – generation of an alphanumeric-character code using special characters, including, in addition to numbers and letters of different registers, 9 characters long

The number after the decimal point specifies the exact number of characters in the verification code.