Incident Response - Out of band communication

Heyo all,

I am on an IR team. Preparing the team via training and drafting procedures as much as possible. In the scenario that we are unable to communicate via domain joined products such as Outlook/MS Teams/ect, what do you guys recommend?

I was thinking Slack (non-domain joined of course), with our personal mobile phone numbers as a backup to slack.

Thoughts?

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