diff --git a/pySim/ts_31_102.py b/pySim/ts_31_102.py
index dc674b25..a90139d7 100644
--- a/pySim/ts_31_102.py
+++ b/pySim/ts_31_102.py
@@ -466,11 +466,13 @@ class EF_UST(EF_UServiceTable):
 
         def do_ust_service_activate(self, arg):
             """Activate a service within EF.UST"""
-            self._cmd.card.update_ust(int(arg), 1)
+            selected_file = self._cmd.lchan.selected_file
+            selected_file.ust_update(self._cmd, [int(arg)], [])
 
         def do_ust_service_deactivate(self, arg):
             """Deactivate a service within EF.UST"""
-            self._cmd.card.update_ust(int(arg), 0)
+            selected_file = self._cmd.lchan.selected_file
+            selected_file.ust_update(self._cmd, [], [int(arg)])
 
         def do_ust_service_check(self, arg):
             """Check consistency between services of this file and files present/activated.
diff --git a/pySim/ts_31_102_telecom.py b/pySim/ts_31_102_telecom.py
index a0098c72..575ccaed 100644
--- a/pySim/ts_31_102_telecom.py
+++ b/pySim/ts_31_102_telecom.py
@@ -120,7 +120,26 @@ class EF_UServiceTable(TransparentEF):
             cmd.lchan.select_file(self)
         return num_problems
 
+    def ust_update(self, cmd, activate=[], deactivate=[]):
+        service_data, sw = cmd.lchan.read_binary()
+        service_data = h2b(service_data)
 
+        for service in activate:
+            nbyte, nbit = EF_UServiceTable._bit_byte_offset_for_service(service)
+            if nbyte > len(service_data):
+                missing = nbyte - service_data
+                service_data.extend(missing * "00")
+            service_data[nbyte] |= (1 << nbit)
+
+        for service in deactivate:
+            nbyte, nbit = EF_UServiceTable._bit_byte_offset_for_service(service)
+            if nbyte > len(service_data):
+                missing = nbyte - service_data
+                service_data.extend(missing * "00")
+            service_data[nbyte] &= ~(1 << nbit)
+
+        service_data = b2h(service_data)
+        cmd.lchan.update_binary(service_data)
 
 # TS 31.102 Section 4.4.2.1
 class EF_PBR(LinFixedEF):