  Microsoft Teams is a collaboration and communication platform developed by
Microsoft that replaces and extends Microsoft Skype for Business. It differs
from Skype for Business by the fact that it exists only as part of the
Microsoft 365 products whereas Skype for Business can be deployed completely or
partly on-premise. During the pandemic emergency in 2020 and 2021 Microsoft
Teams has increased dramatically its base of users as most of the meetings and
the communications had to be conducted in virtual environments by users working
remotely. Microsoft Teams allows users to collaborate sending and sharing
information virtually with anyone internal or external to the an organization
with PCs and mobile devices, therefore it requires a careful review of all the
security configurations and procedures within the organization. Microsoft Teams
infrastructure can also be integrated with PSTN telephone services, natively
within the Microsoft 365 services or by integrating other PSTN service
providers. Therefore, its architecture extends the perimeter that could be
exploited for an attack. Microsoft Teams features can also be extended by Apps.
There are hundreds of Apps developed by Microsoft and by other companies to
address the various needs of modern collaboration. "Walkie Talkie", one of
those Apps, transforms the Teams client installed in a mobile phone into a
Walkie Talkie communication device for registered users. The goal of this paper
is to describe different Teams' usage scenarios and to analyse Teams' PSTN and
Teams' Walkie Talkie communication scenarios describing forensics procedures to
investigate inappropriate users' conduct.
