Numbers can be purchased only directly from within your Dashboard in the main Account. Once you do, you can assign a Number from within your Numbers overview:
- Click on the person icon.
- From the drop-down menu select the Subaccount that you wish to allocate the number to. Then just click on 'Save'.
Remember that a Number can only be assigned and used by one Account at the same time, so once assigned, the main Account or any other Subaccount won’t receive any messages related to this Number anymore.