Resource Account Numbering

We are using direct routing but need to move groups from the phone system to Teams. Can I assign a number from my existing SIP trunks to the resource account or do I need a number from Microsoft? If it is an MS number do you have to pay for a toll number.

If I can allocate a number to the user in MS365 from my existing numbers (virtual phone system user licence applied) should it pull across to Teams?