The operation has timed out using SAP PI Soap Service

Dear All,

We are having one Proxy to Soap Synchronous Scenarios.Service is Exposed to Some Third Party System, Third Party System Send Data to SAP System using the Service Provided by SAP PI ,after successful Processing the Message SAP Return some message back. We are daily getting below message when we invoke SAP PI Service from Third Party System 5-6 times "The operation has
timed out"

"Error: 4/7/2014 12:14:33 PM System.Net.WebException: The
operation has timed out

  at
System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest
request)

    at
System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest
request)

  at
System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName,
Object[] parameters)

    at
PO.NDPL.InterfaceProcessors.poCustServiceReference.XI_1ee9ca4ff0e43d8084f45800464ceb1f_Service.PlannedOutage_OMS_Out(order[]
getCustomerList

Please Help me to resolve the Issue . PI Version 7.4 Dual Stack

Regards

Pushpendra