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Spam Likely

Spam Likely

Apply for branded call

Branded Call

Phone carriers may mark certain phone numbers as “Spam Likely”. This would lead to your outbound calls to have a low call pickup rate, and can sometimes lead to telephony providers banning your number / account.

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Check whether your number is marked as spam likely

Check your outbound call log to see if the call was not connected due to SIP error code 608. If that’s the case, that means it’s rejected due to marked as spam likely. But it’s not guaranteed that all calls rejected with spam likely will be marked as error code 608. There are a couple of external API / services that can help you check if your number is marked as spam likely. This is not a perfect match as each carrier might have their own rules and database, but you can use it as a reference:
  • Nomorobo: can use the app or use the API to check against its database to see if the number is marked as spam likely.
  • IPQualityScore: can check the phone number reputation score.

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Actions you can take

Retell provides two services to improve your call pickup rate:
  1. Verified Phone: Retell will register your number with the phone carrier, which will not be marked as spam by carriers.
  2. Branded Call: Callee will see your number as your business name, instead of the generic Retell number.

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iOS 26 Call Screening

iPhones running on iOS 26 may deploy a call screening feature. At the beginning of the call, Siri will ask unknown numbers to provide their name and reason for calling. To pass this screen, enhance your agent prompt to respond with a name and reason when questioned.
iOS Call Screen

iOS Call Screen

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