when any one call web service ,it should called its default method

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C#3.5

webservice

Good morning ,
i am creating one web service where i have multiple methods say test1() ,test2() ,test3() , etc.
Now test1() is default method or say its mail method.
When i or any one call my web service by default it should called test1().
so is there any possibility?
I tried with these
1) in web.config ,

<authentication mode="Forms">
      <forms loginUrl="~/Default.aspx" timeout="2880" defaultUrl="~/WebService.asmx?op=test1" name=".AspNetAuth" />
    </authentication>

dont work then i try

2) IIS , i was trying to put in Default Document -> WebService.asmx?op=test1 but its not accepting '?'

so is there any way do this , let me know .
Thank you.