diff --git a/apps/bff/src/modules/subscriptions/sim-management/services/sim-call-history.service.ts b/apps/bff/src/modules/subscriptions/sim-management/services/sim-call-history.service.ts
index 7705b072..710857fe 100644
--- a/apps/bff/src/modules/subscriptions/sim-management/services/sim-call-history.service.ts
+++ b/apps/bff/src/modules/subscriptions/sim-management/services/sim-call-history.service.ts
@@ -146,8 +146,13 @@ export class SimCallHistoryService {
           continue;
         }
 
-        // Parse duration (320 = 32.0 seconds)
-        const durationSec = Math.round(parseInt(durationStr, 10) / 10);
+        // Parse duration - format is MMSST (minutes, seconds, tenths)
+        // e.g., 36270 = 36 min 27.0 sec, 320 = 0 min 32.0 sec
+        const durationVal = durationStr.padStart(5, "0"); // Ensure at least 5 digits
+        const minutes = parseInt(durationVal.slice(0, -3), 10) || 0; // All but last 3 digits
+        const seconds = parseInt(durationVal.slice(-3, -1), 10) || 0; // 2 digits before last
+        // Last digit is tenths, which we ignore
+        const durationSec = minutes * 60 + seconds;
 
         // Parse charge: use tokens * 10 yen, or alt charge if location is "他社"
         let chargeYen: number;