What is number warm-up?
Number warm-up is the practice of bringing a new phone number into outbound calling gradually, instead of starting it at full volume on day one.
Why it matters for sales teams
A brand-new number has little or no calling history yet, so carriers and their analytics partners have little to judge it by when its first calls go out. The FCC notes that legitimate calls can be blocked by mistake when their pattern looks like that of unwanted robocalls, which is the risk that warming up a new number is meant to reduce.
Example
A team adds a new local number to the pool of numbers its reps call from each day. Rather than placing a full day of calls from it at once, the team lets its use build up over time alongside older numbers that already have a calling history with carriers.
Number warm-up vs number rotation
Warm-up is about how one new number starts out in outbound calling. Number rotation is about how calls are spread across numbers that are already in use, and teams often use the two ideas together to protect each number's reputation over time.