No, users can only activate MultiLine on one phone or tablet at a time.
If the user switches phones or tablet, when they activate MultiLine on the new device, access to MultiLine on the other device will be deactivated.
Note: if the user is using the same phone or tablet and switches SIM cards, they must follow the steps here: Switch SIM card.
Note: a user can activate MultiLine on a phone or tablet and use MultiLine Desktop, Microsoft Teams, or MultiLine for Salesforce.