Add minimal USSD support to test extension number

Change-Id: Ib19331f9c6476ac01bf729790dfd63c56de86a89
diff --git a/example/default-suites.conf b/example/default-suites.conf
index 3fd1322..5cf19ef 100644
--- a/example/default-suites.conf
+++ b/example/default-suites.conf
@@ -1,12 +1,18 @@
 - sms:sysmo
 - aoip_sms:sysmo
+- ussd:sysmo
+- aoip_ussd:sysmo
 - voice:sysmo
 - sms:trx-b200
 - aoip_sms:trx-b200
+- ussd:trx-b200
+- aoip_ussd:trx-b200
 - voice:trx-b200
 - sms:trx-sysmocell5000
 - aoip_sms:trx-sysmocell5000
 - voice:trx-sysmocell5000
+- ussd:trx-sysmocell5000
+- aoip_ussd:trx-sysmocell5000
 - smpp
 - aoip_smpp
 - aoip_encryption