This action is used to determine if a USSD flow initiated by an end-user includes any sub-code options when the USSD code was dialed. The USSD sub-code will then be identifed as a variable in the workflow using the term [[Session:param:1]], with the 1 being the sub-code. For example, if when initiating the USSD workflow, the end-user dialed *100*1#, the variable will be identified as [[Session:param:1]], with the '1' the sub-code.
Up to 9 levels of sub-codes are supported, with each of the sub-code needing to be individually extracted e.g. [[Session:param:9]].