code: public function getBillingAccountServices()
      {
      	$serviceList = json_decode(self::getClient()->getBillingAccountServices($this->billingAccount));
  
      	$services = array();
  
      	foreach ($serviceList as $service) 
      	{
      		$services[] = new TelephonyAccountService($service, $this);
      	}
      	return $services;
      }
docs: Get services associated with this billing account.
  @return array billing accoun services