diff --git a/app/src/main/kotlin/com/tutpro/baresip/UserAgent.kt b/app/src/main/kotlin/com/tutpro/baresip/UserAgent.kt
index b5a07218..2a217436 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/UserAgent.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/UserAgent.kt
@@ -36,16 +36,19 @@ class UserAgent(val uap: Long, virtualAccount: Account? = null) {
 
     fun calls(dir: String = ""): ArrayList<Call> {
         val result = ArrayList<Call>()
-        for (c in BaresipService.calls)
-            if ((c.ua == this) && ((dir == "") || c.dir == dir)) result.add(c)
+        synchronized(BaresipService.calls) {
+            for (c in BaresipService.calls)
+                if ((c.ua == this) && ((dir == "") || c.dir == dir)) result.add(c)
+        }
         return result
     }
 
-    // Returns call of UA that was added last or NULL
     fun currentCall(): Call? {
-        for (c in BaresipService.calls.reversed())
-            if (c.ua == this)
-                return c
+        synchronized(BaresipService.calls) {
+            for (c in BaresipService.calls.reversed())
+                if (c.ua == this)
+                    return c
+        }
         return null
     }