A sender ID can be one of 3 types: alpha, numeric, and short code.
Note: Only numeric and short code sender ID’s can be replied to.
Alpha sender IDs consist of letters (a-z) and digits (0-9), other characters may be used but may not be supported by all phones and operators. Numeric sender IDs should be in an international format e.g. +447712312312. Alpha sender IDs are usually limited to a length of 11 characters and numeric sender IDs are limited to 16 digits. Short codes are typically 5 or 6 digits but this can vary by country.
The use of a dynamic sender ID feature is not allowed in all countries, as it is subject to the local compliance and carrier rules.