> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/external-user-call-via-microsoft-teams.md).
# External user call via Microsoft Teams
### Synopsis
| Field | Value |
| -------------------- | ----------------------------------------- |
| Activation Period | 14 Days |
| Training Period | 30 Days |
| Test Period | 10 Minutes |
| Deduplication Period | 1 Day |
| Required Data | Office 365 Audit |
| Detection Modules | Identity Threat Module |
| Detector Tags | Microsoft Teams |
| ATT\&CK Tactic | Initial Access (TA0001) |
| ATT\&CK Technique | Phishing: Spearphishing Voice (T1566.004) |
| Severity | Informational |
### Description
An external user called a user in the organization via Microsoft Teams.
### Attacker's Goals
Attackers may leverage Microsoft Teams to conduct voice phishing attacks by exploiting trusted communication channels with users inside the organization.
### Investigative actions
* Confirm that the external tenant and external user are authorized to call users in the organization.
* Check external domain reputation.
* Follow further actions performed by the user who participated in the call.
* Verify if the user account was compromised or was a victim of a voice phishing campaign.
### Variations
A first seen external user with a suspicious name initiated a Microsoft Teams call
**Synopsis**
| Field | Value |
| ----------------- | ----------------------------------------- |
| ATT\&CK Tactic | Initial Access (TA0001) |
| ATT\&CK Technique | Phishing: Spearphishing Voice (T1566.004) |
| Severity | Medium |
**Description**
A first seen external user with a suspicious name successfully called via Microsoft Teams a user in the organization.
**Attacker's Goals**
Attackers may leverage Microsoft Teams to conduct voice phishing attacks by exploiting trusted communication channels with users inside the organization.
**Investigative actions**
* Confirm that the external tenant and external user are authorized to call users in the organization.
* Check external domain reputation.
* Follow further actions performed by the user who participated in the call.
* Verify if the user account was compromised or was a victim of a voice phishing campaign.
An external user with a suspicious name initiated a Microsoft Teams call
**Synopsis**
| Field | Value |
| ----------------- | ----------------------------------------- |
| ATT\&CK Tactic | Initial Access (TA0001) |
| ATT\&CK Technique | Phishing: Spearphishing Voice (T1566.004) |
| Severity | Low |
**Description**
An external user with a suspicious name called via Microsoft Teams a user in the organization.
**Attacker's Goals**
Attackers may leverage Microsoft Teams to conduct voice phishing attacks by exploiting trusted communication channels with users inside the organization.
**Investigative actions**
* Confirm that the external tenant and external user are authorized to call users in the organization.
* Check external domain reputation.
* Follow further actions performed by the user who participated in the call.
* Verify if the user account was compromised or was a victim of a voice phishing campaign.
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