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? USSD Integration Guide How do I set up a USSD dialog? What is the maximum number of characters for a USSD message? Form Factor & SIM specifications Comments 0 comments Please sign in to leave a comment.