function Invoke-AutotaskProvision {
    param (
        [Parameter(Mandatory)]
        [string]$CompanyName,

        [Parameter(Mandatory)]
        [string]$PhoneNumber,

        [Parameter(Mandatory)]
        [hashtable]$Credentials
    )

    if (-not $Credentials["AutotaskURL"] -or -not $Credentials["AutotaskIntCode"] -or -not $Credentials["AutotaskUsername"] -or -not $Credentials["AutotaskSecret"]) {
        throw "Missing Autotask credentials in hashtable."
    }

    $BaseURL = $Credentials["AutotaskURL"]
    $Url = "https://$BaseURL/atservicesrest/v1.0/companies"

    $Headers = @{
        "ApiIntegrationcode" = $Credentials["AutotaskIntCode"]
        "UserName"           = $Credentials["AutotaskUsername"]
        "Secret"             = $Credentials["AutotaskSecret"]
        "Content-Type"       = "application/json"
    }

    $Body = @{
        companyName     = $CompanyName
        companyType     = 1
        phone           = $PhoneNumber
        ownerResourceID = 4
    } | ConvertTo-Json -Depth 3

    try {
        $Response = Invoke-RestMethod -Uri $Url -Method Post -Headers $Headers -Body $Body
        $Response.itemId, $Response.id, $Response.companyID, $Response.item.id | Where-Object { $_ } | Select-Object -First 1
    } catch {
        throw "[Autotask] Provisioning failed: $($_.Exception.Message)"
    }
}