For installation as such, you don't need any license number. But if your installation media is not pre-pidded, you may need the PID. However, if you are license-audited, and you don't have your license papers in order, the situation can become awkward.
However, I am not sure that this old license is of much value. Because that license is for the version of SQL Server you installed back then, and I really hope that you are installing SQL Server 2022, the recent version. But for this, you need a new license. I don't know if there is an "upgrade price", but that would typically be from the most recent version, not from a version "many years ago".
As for what phone number to call, you could try with your local Microsoft subsidiary, but since licenses are often sold through resellers, I am not sure how of much help they can be.