Explanation:

✅ B. Provision a toll-free phone number at least 8 weeks before go-live
To support automated outbound SMS messages for package shipping notifications, provisioning a toll-free phone number is the most suitable option for Universal Containers (UC). Toll-free numbers are widely supported for A2P (Application-to-Person) messaging, offer high deliverability rates, and are ideal for high-volume, automated SMS campaigns like shipping notifications. They are also recognized by customers as legitimate business numbers, enhancing trust. Provisioning at least 8 weeks before go-live allows sufficient time for carrier registration, compliance with regulations (e.g., 10DLC or TCR requirements in the US), and testing to ensure reliable message delivery. This timeline accounts for carrier approval processes, which can take several weeks, especially for high-volume use cases.

❌ A. Provision a short code phone number at least 8 weeks before go-live
While short codes are excellent for high-volume SMS campaigns due to their high throughput and deliverability, they are typically more expensive and complex to provision than toll-free numbers. Short codes require extensive carrier approval processes, which can take 8–12 weeks or longer, and are better suited for marketing campaigns or time-sensitive alerts rather than transactional notifications like shipping updates. For UC’s use case of automated package notifications, a toll-free number is more cost-effective and sufficient, making this option less optimal.

❌ C. Provision a long code phone number at least 2 weeks before go-live
Long code phone numbers (10-digit numbers) are suitable for low-volume SMS or two-way communication but are not ideal for high-volume automated outbound SMS like UC’s shipping notifications. Long codes face stricter carrier restrictions under 10DLC regulations, have lower throughput, and are more likely to be filtered as spam, which could disrupt reliable delivery. Additionally, while provisioning a long code is faster than a toll-free number, the 2-week timeline may not provide enough time for proper registration, testing, and compliance with carrier requirements, risking delays or blocked messages.

Reference:
🔗 Salesforce Help: Set Up SMS Messaging in Marketing Cloud Engagement
🔗 Salesforce Help: Messaging Compliance and Best Practices