The paper demonstrates a vulnerability in Android's telephony stack that allows a malicious app (without special permissions) to even when the device is in "blocked" states — e.g., Do Not Disturb mode , call barring enabled by enterprise policies, or even when the phone is SIM-locked due to unpaid bills.
: If you recently reported your phone lost or stolen and then found it, your carrier may still have the outgoing line "blacklisted."
(like "Call Failed" or "Not registered on network") when you try to dial? unblock outgoing calls
On iPhone, check > Phone > Call Blocking & Identification to see if any apps are managing your calls. 5. Carrier-Specific Codes
The researchers found that Android's TelephonyManager and ITelephony AIDL interface allowed apps to place calls via ITelephony.endCall() and ITelephony.answerRingingCall() race conditions, bypassing the usual outgoing call restrictions. Verify your billing
Navigate to your > Supplementary services > Call barring .
Verify your billing. Most carriers automatically suspend outgoing services if a payment is missed. Do Not Disturb mode
Check Focus/Do Not Disturb: On iPhone or Android, ensure you aren't in a restrictive mode that limits app permissions.
Call barring is a network feature that allows you to stop certain types of calls. If "All Outgoing Calls" is toggled on, your phone will stay silent. Navigate to your Call Settings. Find the Call Barring option. Ensure all "Outgoing" categories are turned off.
Confirm your plan limits. If you are on a prepaid plan, you may have exhausted your minutes or credits.
(If you need the PDF and don’t have access, try the authors’ university pages or arXiv — though the final version is behind a paywall.)