aoip: add osmo-stp, now required for aoip runs

Change-Id: I35d4cb0d173eec240bccc1f3a5965a774b7b3506
diff --git a/suites/aoip_sms/mo_mt_sms.py b/suites/aoip_sms/mo_mt_sms.py
index 8eba842..217d807 100755
--- a/suites/aoip_sms/mo_mt_sms.py
+++ b/suites/aoip_sms/mo_mt_sms.py
@@ -6,10 +6,12 @@
 mgcpgw = suite.mgcpgw(bts_ip=bts.remote_addr())
 msc = suite.msc(hlr, mgcpgw)
 bsc = suite.bsc(msc)
+stp = suite.stp()
 ms_mo = suite.modem()
 ms_mt = suite.modem()
 
 hlr.start()
+stp.start()
 msc.start()
 mgcpgw.start()