code: public ArrayList<OvhDirectoryHeadingPJ> billingAccount_service_serviceName_directory_getDirectoryServiceCode_GET(String billingAccount, String serviceName, String apeCode) throws IOException {
  		String qPath = "/telephony/{billingAccount}/service/{serviceName}/directory/getDirectoryServiceCode";
  		StringBuilder sb = path(qPath, billingAccount, serviceName);
  		query(sb, "apeCode", apeCode);
  		String resp = exec(qPath, "GET", sb.toString(), null);
  		return convertTo(resp, t13);
  	}
docs: Get directory service code from an APE code ( principal activity of the firm code )
  
  REST: GET /telephony/{billingAccount}/service/{serviceName}/directory/getDirectoryServiceCode
  @param apeCode [required]
  @param billingAccount [required] The name of your billingAccount
  @param serviceName [required]