moved utility functions out from main activity

app/src/main/kotlin/com/tutpro/baresip/Call.kt

@@ -1,10 +1,33 @@
 package com.tutpro.baresip
 
 import android.text.TextWatcher
+import java.util.ArrayList
 
 class Call(val ua: String, val call: String, val peerURI: String, var status: String,
            val dtmfWatcher: TextWatcher?) {
+
     var hold: Boolean = false
     var security: Int = 0
     var zid: String = ""
+
+    companion object {
+
+        fun uaCalls(calls: ArrayList<Call>, ua: String): ArrayList<Call> {
+            val result = ArrayList<Call>()
+            for (i in calls.indices) {
+                if (calls[i].ua == ua) result.add(calls[i])
+            }
+            return result
+        }
+
+        fun callIndex(calls: ArrayList<Call>, ua: String, call: String): Int {
+            for (i in calls.indices) {
+                if (calls[i].ua.equals(ua) && calls[i].call == call)
+                    return i
+            }
+            return -1
+        }
+
+
+    }
 }