Common causes: 

• international dialing enabled,
• accidental dialing,
• shared device usage,
• SIM moved to another device, 

• roaming-related dialing behavior.

   

Customer checks: 

• verify call log timeframe,
• check if others had access,
• confirm roaming/IDD settings,
• review add-on packages.

If customer disputes: 

• explain escalation path (billing specialist review),
• what evidence helps (dates/times, device possession),
• expected timelines.