There are different costs and benefits between multi-line or single line smrtDialer. (Read more here >>)
If you have a single line subscription and you want to upgrade to a multi-line one, you simply need to access your upper right corner Dashboard - as an Account Owner.
Select Billing&Logs and then click on Products.
Here, along with all the smrtPhone subscriptions that you purchased, you can see the option to Upgrade > Upgrade Dialer.
Select this option and then confirm your choice. And now you can enjoy the multi-line features.
Please, be aware that any change in product brings different fees. To find more, check our collection regarding Sales, Billing, and Pricing.
Of course, there will be always the opportunity to downgrade from a multi-liner to a single line smrtDialer.
Note: This action is only permitted to the Account Owner, not to Users or Administrators and it requires a smrtPhone subscription.