/**
 * Custom SIP header for phone transfers with a dynamic variable reference.
 * The value is a variable name that will be resolved at runtime.
 * Value is not validated here since it will be substituted with actual value later.
 */
export interface CustomSipHeaderWithDynamicVariable {
    /** The SIP header name (e.g., 'X-Customer-ID') */
    key: string;
    /** The dynamic variable name to resolve */
    value: string;
}