diff --git a/backend/src/services/contract.service.ts b/backend/src/services/contract.service.ts
index 74f284df..823ed482 100644
--- a/backend/src/services/contract.service.ts
+++ b/backend/src/services/contract.service.ts
@@ -356,7 +356,8 @@ function normalizeMobileNetwork(value: unknown): string | null {
 const CONTRACT_SCALAR_FIELDS = [
   'customerId', 'type', 'contractCategoryId', 'status', 'addressId', 'billingAddressId',
   'bankCardId', 'identityDocumentId', 'salesPlatformId', 'previousContractId', 'providerId',
-  'tariffId', 'providerName', 'tariffName', 'customerNumberAtProvider', 'orderNumberAtSalesPlatform',
+  'tariffId', 'providerName', 'tariffName', 'customerNumberAtProvider', 'contractNumberAtProvider',
+  'orderNumberAtSalesPlatform',
   'customerNumberAtSalesPlatform', 'contractNumberAtSalesPlatform', 'priceFirst12Months',
   'priceFrom13Months', 'priceAfter24Months', 'startDate', 'endDate', 'cancellationPeriodId',
   'contractDurationId', 'commission', 'portalUsername', 'stressfreiEmailId',