Exception::System.Net.WebException: The request failed with HTTP status 401: Unauthorized [:'(]

I am trying access a webservice through my web application but i am getting this error, can you please help me to get rid of this error? 

Exception::System.Net.WebException: The request failed with HTTP status 401: Unauthorized.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at FORIS.TelCRM.RequestManagement.CustomerCare.UI.RequestManagementWSAddRemoveService.AddRemoveServices.GetBalance(String InputXML)
   at FORIS.TelCRM.RequestManagement.CustomerCare.UI.AddRemSHiddenForm.Page_Load(Object sender, EventArgs e)
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Thanks

Awais
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