Microsoft Teams offers the possibility to integrate your own communication infrastructure, e.g. your own SIP provider for phone services. This requires a Microsoft-certified and -approved Session Border Controller. During the security analysis of this federation, Moritz Abrell identified several vulnerabilities that allow an external, unauthenticated attacker to perform toll fraud. This talk is a summary of this analysis, the identified security issues and the practical exploitation as well as the manufacturer's capitulation to the final fix of the vulnerabilities.