If you are using a provisioning server the phone would upload its Mac-directory.xml file. You then simply rename it to the new Mac. If you are not using a provisioning server and have no way of setting one up the numbers will be lost.
Replied via a mobile device
Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels. Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's