# BR-DE-6

Source: https://xmlvalid.com/rules/BR-DE-6

> Das Element "Seller contact telephone number" (BT-42) muss übermittelt werden.

- Level: error
- Rule sets: XRechnung 3.0 rules (UBL) 2.6.0
- Context: `/ubl:Invoice/cac:AccountingSupplierParty/cac:Party/cac:Contact | /cn:CreditNote/cac:AccountingSupplierParty/cac:Party/cac:Contact`
- Test: `cbc:Telephone[boolean(normalize-space(.))]`

> Das Element "Seller contact telephone number" (BT-42) muss übermittelt werden.

- Level: error
- Rule sets: XRechnung 3.0 rules (CII) 2.6.0
- Context: `/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTradeParty/ram:DefinedTradeContact`
- Test: `ram:TelephoneUniversalCommunication/ram:CompleteNumber[boolean(normalize-space(.))]`

## Why it fails

- The seller contact has no telephone number: `cac:Contact/cbc:Telephone` (`ram:TelephoneUniversalCommunication/ram:CompleteNumber` in CII) is missing or empty.

## How to fix it

- Add a telephone number to the seller contact. Any format passes the rule; the international form (+49 30 1234567) is the safest.

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