> For the complete documentation index, see [llms.txt](https://docs.truecaller.com/truecaller-for-business/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.truecaller.com/truecaller-for-business/features/call-me-back/why-in-certain-webhook-scenarios-the-client_number-is-returned-as-phone-number-not-available.md).
# Why in certain webhook scenarios the "client\_number" is returned as "Phone Number Not Available"?
The "client\_number" will appear as "Phone Number Not Available" in the following cases:
1. The user received the call on their **unregistered SIM.**
2. The user’s **SIM could not be detected** on the device.
3. The user **did not provide consent** to share the secondary SIM phone number.
In these cases, we do not share the actual phone number, and we pass this status accordingly in the "client\_number" field and populate the "alternate\_number" field with the phone number the user has registered with Truecaller.
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