자체 해결
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1. <uses-permission android:name="android.permission.CALL_PHONE" />  추가하구요

2.
public boolean shouldOverrideUrlLoading(WebView view, String url) {      
    if(url.startswith("tel:")) {
        Intent call_phone = new Intent(Intent.ACTION_VIEW , Uri.parse(url)) ;
        // 현재의 activity 에 대해 startActivity 호출
        startActivity(call_phone) ;
         return true ;
    }
    view.loadUrl(url);      
    return true;  
   }