Having your fax number taken over by XOIP takes around 5-7 business days. To do this, you will need to sign up for a one-year, or longer, XOIP subscription. If a number needs to be ported from an ISDN2-subscription, XOIP needs to take over all numbers from this registration. If this is the case, you will need to send a message to firstname.lastname@example.org. They will forward you the necessary information.
All XOIP services are available on ported numbers. After porting your number will no longer be available for use with your own fax machine or phone. Faxes and voicemail messages are forwarded to your email. You can find more information here.