src/Payum/Payex/Api/RecurringApi.php
public function start(array $parameters)
    {
        $parameters['accountNumber'] = $this->options['account_number'];

        if (isset($parameters['orderId'])) {
            $parameters['orderID'] = $parameters['orderId'];
            unset($parameters['orderId']);
        }

        //Deprecated, set to blank.
        $parameters['notifyUrl'] = '';

        $parameters['hash'] = $this->calculateHash($parameters, array(
            'accountNumber',
            'agreementRef',
            'startDate',
            'periodType',
            'period',
            'alertPeriod',
            'price',
            'productNumber',
            'orderID',
            'description',
            'notifyUrl',
        ));

        return $this->call('Start', $parameters, $this->getPxRecurringWsdl());
    }
public function start(array $parameters)
    {
        $parameters['accountNumber'] = $this->options['account_number'];

        if (isset($parameters['orderId'])) {
            $parameters['orderID'] = $parameters['orderId'];
            unset($parameters['orderId']);
        }

        //Deprecated, set to blank.
        $parameters['notifyUrl'] = '';

        $parameters['hash'] = $this->calculateHash($parameters, array(
            'accountNumber',
            'agreementRef',
            'startDate',
            'periodType',
            'period',
            'alertPeriod',
            'price',
            'productNumber',
            'orderID',
            'description',
            'notifyUrl',
        ));

        return $this->call('Start', $parameters, $this->getPxRecurringWsdl());
    }
@link http://www.payexpim.com/technical-reference/pxrecurring/pxrecurring-start/

@param array $parameters

@return array