In addition of your US phone number you receive a temporary landline number from your origin country and you can forward your current cell phone number to this landline. Then it will forward automatically all received calls to your US phone number. There is no extra cost for you or for the caller. You have to contact your current carrier to know how to set up call forwarding as it might incur a fee. Please note only calls are forwarded. No text.
You can purchase this option for a new activation, you only need to provide your SIM serial number. Or you can extend the service, you only need to provide your US phone number but it must be active. Days will be added based on the expiry date of your plan.
For a recently activated sim card the landline number will be issued within 24 hours maximum. For a non-activated sim the landline number will be emailed to you upon the sim activation.