Google added a checkCallingPermission for ITelephony methods and restricted direct access to the telephony stack from third‑party apps without MANAGE_ONGOING_CALLS (signature permission).
Check Focus/Do Not Disturb: On iPhone or Android, ensure you aren't in a restrictive mode that limits app permissions. unblock outgoing calls
Here is a comprehensive guide on how to identify the cause and unblock outgoing calls on any device. Check Your Carrier Status and Plan unblock outgoing calls
"Unblocking Outgoing Calls on Android: A Practical and Generic Attack" unblock outgoing calls
Android 9–12 (patched in later security updates). The vulnerability required no extra permissions — just a background app.
Examine Security Apps: Call-blocking apps (like Truecaller or Hiya) occasionally misidentify your outgoing attempts as errors or block them due to permission conflicts.