In order to call this API endpoint, user needs to have [ReadCompanyCallLog] permission.

It means that in order to read the call log of an entire account (call data of all extensions under an account) you need to login with the admin extension 101 or other extensions with the admin role.

If you login with a normal user extension (User role) use this endpoint '/restapi/v1.0/account/~/extension/~/call-log'

The main reason is this is an admin root access level to read the company level log and access the call log of all extension under the account.

Active Calls, Account level Call Log Records, and Extension level Call Log Records require the ReadCallLog API permission.

ref: https://developers.ringcentral.com/guide/voice/call-log/reading-call-log

more info: https://forums.developers.ringcentral.com/questions/162/call-logs-for-individual-accounts.html