When placing outbound calls, the caller ID number you use plays a critical role in how carriers evaluate and deliver those calls. Calls made using a custom caller ID (your own number and not a Ring.io company or personal number) may be more likely to appear as Spam or Scam Likely on the recipient’s device when compared to calls made using a Ring.io hosted number within your account.
This behavior is primarily driven by STIR/SHAKEN attestation levels, which mobile carriers use to assess the legitimacy of a call.
Understanding STIR/SHAKEN Attestation Levels
STIR/SHAKEN is an industry framework used by carriers to authenticate caller ID information and reduce spoofed or fraudulent calls. Each outbound call is assigned one of three attestation levels:
Attestation Level Description
A (Full Attestation) The service provider knows the caller and can verify that the caller is authorized to use the calling number.
B (Partial Attestation) The service provider knows the caller but cannot verify that they are authorized to use the calling number.
C (Gateway Attestation) The call origin cannot be verified. The provider is simply passing the call through.
Carriers use these levels—along with reputation analytics—to determine whether a call should be delivered normally, labeled as spam, or blocked.
Hosted Numbers (Recommended) vs. Custom Caller ID
A hosted number is a number that is:
A number that is purchased or ported into your Ring.io account, and is directly associated with your business identity. As ownership and authorization can be confirmed, hosted numbers typically receive Attestation A.
Benefits of Attestation A:
-Highest trust level with carriers
-Lowest risk of spam labeling
-Better call completion rates
Custom Caller ID (Use your own):
A custom caller ID allows you to present a number that is not hosted or verified in your account (for example, a mobile number or external landline).Since the platform cannot cryptographically verify your right to use that number, these calls usually receive Attestation B or C.
Risks:
-Increased likelihood of spam or scam labeling
-Greater sensitivity to carrier reputation filters
-Inconsistent call delivery
Key Takeaway:
Using a hosted number provides the highest level of caller verification and the best chance of avoiding spam labeling. While custom caller ID can be convenient, it carries inherent trust limitations due to lower attestation levels, which may negatively impact call delivery.
For reliable outbound calling and optimal answer rates, hosted numbers are strongly recommended.