diff --git a/scenarios/check.sh b/scenarios/check.sh
index e038f2ae..26f3da35 100755
--- a/scenarios/check.sh
+++ b/scenarios/check.sh
@@ -82,12 +82,19 @@ function run_sipp
   if [ -f ${SCEN_CHECK_DIR}/sipp_scenario_responder.xml ]; then
     ${BASE_DIR}/sipp.sh -d ${DOMAIN} -r ${SCEN_CHECK_DIR}/sipp_scenario_responder_reg.xml &> /dev/null
     ${BASE_DIR}/sipp.sh -d ${DOMAIN} -r ${SCEN_CHECK_DIR}/sipp_scenario_responder.xml &> /dev/null &
+    responder_pid=$!
   fi
   # let's fire sipp scenario
   ${BASE_DIR}/sipp.sh -d ${DOMAIN} $1
   status=$?
 
   if [ -f ${SCEN_CHECK_DIR}/sipp_scenario_responder.xml ]; then
+    ps -p${responder_pid} &> /dev/null
+    ps_status=$?
+    if [ ${ps_status} -eq 0 ]; then
+      echo "sipp responder not finished yet. Waiting 5 secs"
+      sleep 5
+    fi
     ${BASE_DIR}/sipp.sh -d ${DOMAIN} -r ${SCEN_CHECK_DIR}/sipp_scenario_responder_unreg.xml &> /dev/null
   fi