With Scaler, Twilio will spread your outbound messaging traffic evenly across all phone numbers in your Number Pool. When a message is sent from a number pool, the 'From' number is selected from among the numbers not currently in use in your number pool.
When a short code is included in your Number Pool, Twilio will prioritize the short code of the geographic region above the other long codes. For example, if a US short code and US long code is available in your Number Pool. The US short code would always be prioritized first.
Note that if Sticky Sender is enabled, Copilot will prioritize the Sticky Sender mapping before evenly distributing your traffic.