modem: Implement voice calls in modem and add voice suite

Change-Id: Ib402effc830db293f27a877658894e454a93a606
diff --git a/suites/voice/mo_mt_call.py b/suites/voice/mo_mt_call.py
new file mode 100755
index 0000000..f426037
--- /dev/null
+++ b/suites/voice/mo_mt_call.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+from osmo_gsm_tester.test import *
+
+hlr = suite.hlr()
+bts = suite.bts()
+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()
+
+bsc.bts_add(bts)
+bsc.start()
+
+bts.start()
+
+hlr.subscriber_add(ms_mo)
+hlr.subscriber_add(ms_mt)
+
+ms_mo.connect(msc.mcc_mnc())
+ms_mt.connect(msc.mcc_mnc())
+
+ms_mo.log_info()
+ms_mt.log_info()
+
+print('waiting for modems to attach...')
+wait(ms_mo.is_connected, msc.mcc_mnc())
+wait(ms_mt.is_connected, msc.mcc_mnc())
+wait(msc.subscriber_attached, ms_mo, ms_mt)
+
+assert len(ms_mo.call_id_list()) == 0 and len(ms_mt.call_id_list()) == 0
+mo_cid = ms_mo.call_dial(ms_mt)
+mt_cid = ms_mt.call_wait_incoming(ms_mo)
+print('dial success')
+
+assert not ms_mo.call_is_active(mo_cid) and not ms_mt.call_is_active(mt_cid)
+ms_mt.call_answer(mt_cid)
+wait(ms_mo.call_is_active, mo_cid)
+wait(ms_mt.call_is_active, mt_cid)
+print('answer success, call established and ongoing')
+
+sleep(5) # maintain the call active for 5 seconds
+
+assert ms_mo.call_is_active(mo_cid) and ms_mt.call_is_active(mt_cid)
+ms_mt.call_hangup(mt_cid)
+wait(lambda: len(ms_mo.call_id_list()) == 0 and len(ms_mt.call_id_list()) == 0)
+print('hangup success')