How do I activate the unlimited calling bundle in a subscription?

You can change the price plan for your subscription at any time. You can find the subscription formulas at Subscriptions”. You change your price plan here.

Want to select another price plan? If so, your current bundle will continue until expiration and you’ll also get the new bundles from your new price plan. However, you will first use your previous bundles. You'll immediately pay for your new monthly bundle and any usage outside the previous bundle. Your new price plan will be renewed every 30 days. You will receive your next invoice or payment invitation in the month after you switch over, independent of the date of your previous subscription.