Which USSD prefix does EMnify support? Jean-Eudes October 26, 2018 06:37 Updated Follow EMnify USSD services only support prefixes from 100 to 109. For detailed information regarding USSD, please read the USSD Integration Guide. Related articles Which USSD protocols does EMnify support? What is the maximum number of characters for a USSD message? USSD Integration Guide USSD Introduction Comments 0 comments Please sign in to leave a comment.