Problem in calling webservice in php

[suhas_clarion]

Hi,
I have site and in that site i want to call a webservice. For calling the webservice it require to pass the customer id to the websservice as a credential and then it gives the access to the methods mentioned in the web service.
I am using SOAP for calling the webservice but i dont know how to send the customer id with soap.
When i use the method setCredentials(), or setHeaders() with customer id as a parameter then it reflects fault with stating that Invalid Credential; Access Denied

Can anybody help me regarding this

Thanks
Suhas
[e-mail]