Index: kernel/generic/include/ipc/ipc.h
===================================================================
--- kernel/generic/include/ipc/ipc.h	(revision fdb9982c4a402d4d9c5df2cc4d6fe1fa66823fb9)
+++ kernel/generic/include/ipc/ipc.h	(revision 3c22f7021df532f9625f32db5da18694b800e183)
@@ -165,5 +165,7 @@
  *                       error is sent back to caller. Otherwise 
  *                       the call is accepted and the response is sent back.
- *                     - the allocated phoneid is passed to userspace 
+ *                     - the hash of the client task is passed to userspace
+ *                       (on the receiving side) as ARG4 of the call.
+ *                     - the hash of the allocated phone is passed to userspace
  *                       (on the receiving side) as ARG5 of the call.
  *
Index: kernel/generic/src/ipc/sysipc.c
===================================================================
--- kernel/generic/src/ipc/sysipc.c	(revision fdb9982c4a402d4d9c5df2cc4d6fe1fa66823fb9)
+++ kernel/generic/src/ipc/sysipc.c	(revision 3c22f7021df532f9625f32db5da18694b800e183)
@@ -248,4 +248,6 @@
 			/* The connection was accepted */
 			phone_connect(phoneid, &answer->sender->answerbox);
+			/* Set 'task hash' as arg4 of response */
+			IPC_SET_ARG4(answer->data, (sysarg_t) TASK);
 			/* Set 'phone hash' as arg5 of response */
 			IPC_SET_ARG5(answer->data,