Following a Natterbox App upgrade, Salesforce administrators may need to update Field-Level Security (FLS) settings. Stricter security rules in newer package versions require explicit user profile access to standard phone fields. Without this access, the integration cannot query necessary fields, causing CTI errors for your agents in the dialler. You may experience this from Natterbox App package v1.378 and onwards.
How to Identify the Issue
If a user experiences dialler issues, use this quick checklist to confirm if it is an FLS permission block:
User Symptom: The Natterbox dialler fails to transfer/connect, or a red error message is displayed directly in the dialer interface.
CTI Error Message example:

No such column '[Field Name]' on entity '[Object]'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name.
Please reference your WSDL or the describe call for the appropriate names.
Step-by-Step Resolution
We make sure to advise customers of the following if they hit this post-upgrade:
Identify the blocked field and the associated object from the error message.
Go to SF Setup > Object Manager > [Object] > Fields & Relationships > [Field Name].
Click Set Field-Level Security and ensure Visible is checked for their user profiles.
Please note:
Once access is granted to the Home Phone field, the error may move to Other Phone. Granting access to both resolves the issue. If this happens, simply repeat the steps above for the next field.