Fedex API - SATURDAY_DELIVERY

Im having some trouble getting my SATURDAY_DELIVERY tag to work.

I can get the Saturday delivery from the rates and quotes api, so I know the addresses I'm using allow Saturday delivery.

Any help will be greatly appreciated.

I keep getting the following error:

[{"code":"ORGORDEST.SPECIALSERVICES.NOTALLOWED","message":"This special service type is not allowed for the origin/destination pair. Please update and try again","parameterList":[{"key":"SPECIAL_SERVICE_TYPE","value":"SATURDAY_DELIVERY"}]}

I'm wondering if someone else has come across this - Am I doing something wrong here? Iv tried mutiple different payloads with different addresses, iv tried sandbox API, Prod API, tried real addresses, different pickupType, different packagingTypes etc..

Here's my sample payload

$payload = [
    "accountNumber" => [
        "value" => "*******"
    ],
    "labelResponseOptions" => "URL_ONLY",
    "requestedShipment" => [
        "shipDateStamp" => "2025-06-13", // Friday
        "pickupType" => "DROPOFF_AT_FEDEX_LOCATION",
        "serviceType" => "PRIORITY_OVERNIGHT",
        "packagingType" => "FEDEX_BOX", // Required for SATURDAY_DELIVERY in many areas

        "shipper" => [
            "contact" => [
                "personName" => "John Doe",
                "phoneNumber" => "5555555555",
                "companyName" => "Test Sender Inc"
            ],
            "address" => [
                "streetLines" => ["123 Main Street"],
                "city" => "Memphis",
                "stateOrProvinceCode" => "TN",
                "postalCode" => "38116",
                "countryCode" => "US"
            ]
        ],

        "recipients" => [[
            "contact" => [
                "personName" => "Jane Smith",
                "phoneNumber" => "5555551234",
                "companyName" => "Test Receiver LLC"
            ],
            "address" => [
                "streetLines" => ["100 California Street"],
                "city" => "San Francisco",
                "stateOrProvinceCode" => "CA",
                "postalCode" => "94111",
                "countryCode" => "US",
                "residential" => true
            ]
        ]],

        "shippingChargesPayment" => [
            "paymentType" => "SENDER",
            "payor" => [
                "responsibleParty" => [
                    "accountNumber" => [
                        "value" => "*******"
                    ]
                ]
            ]
        ],

        "requestedPackageLineItems" => [[
            "weight" => [
                "units" => "LB",
                "value" => 2
            ]
        ]],

        "shipmentSpecialServices" => [
            "specialServiceTypes" => ["SATURDAY_DELIVERY"]
        ],

        "labelSpecification" => [
            "labelStockType" => "PAPER_4X6",
            "imageType" => "PDF"
        ]
    ]
];

I figured out my issue.

My Ship Date field is incorrect,

"shipDateStamp" needs to be "shipDatestamp"

So it was always passing todays date, which doesn't support Saturday delivery. Assuming it wasn't Thursday or Friday