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Phone numbers are required to send and receive SMS and MMS messages. Before you can start messaging, you need to purchase at least one phone number and assign it to your application.

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Phone Number Types

Chirp offers different types of phone numbers for different use cases:
Standard phone numbers with a local area code. Best for:
  • Regional businesses and services
  • Lower per-message costs
  • Building local trust with customers
Numbers with prefixes like 800, 888, 877, etc. Best for:
  • National campaigns and services
  • Customer support lines
  • Professional brand image
5-6 digit numbers for high-volume messaging. Best for:
  • Marketing campaigns
  • Two-factor authentication
  • Time-sensitive alerts
  • Higher throughput requirements
Custom text-based sender names instead of numbers. Best for:
  • Brand recognition
  • One-way messaging
  • Marketing communications
Number type availability varies by country. View pricing to see what’s available in your region.

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Pricing

Phone numbers have two cost components:
  1. Purchase fee - One-time cost to acquire the number
  2. Monthly rental fee - Recurring cost to maintain the number
See the pricing page for detailed rates.

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Assigning Numbers to Applications

Phone numbers must be assigned to an application before they can send or receive messages. You can assign the same phone number to multiple applications, allowing you to reuse numbers across different projects. Each application uses its own API keys and webhook configuration, so the same number can behave differently depending on which application is handling the message. See Managing Phone Numbers for more information on how to assign phone numbers to your application.
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