Hi,
If by "call" you mean "navigate to", then you should check the following document in SAP CRM wiki space which explains how to construct URL to access WebUI components:
http://wiki.sdn.sap.com/wiki/display/CRM/URL%27s+for+quick+access+to+WebUI
Regards,
Nicolas Busson.
PS: if by "call" you mean "execute a search and get the results", then check the WebserviceTool.