diff --git a/test/mgw_nat_act_bow_onw_tests.erl b/test/mgw_nat_act_bow_onw_tests.erl
new file mode 100644
index 0000000..19d5c57
--- /dev/null
+++ b/test/mgw_nat_act_bow_onw_tests.erl
@@ -0,0 +1,94 @@
+-module(mgw_nat_act_bow_onw_tests).
+-author('Harald Welte <laforge@gnumonks.org>').
+
+-include_lib("eunit/include/eunit.hrl").
+
+-include_lib("osmo_ss7/include/sccp.hrl").
+-include_lib("osmo_ss7/include/isup.hrl").
+-include_lib("osmo_ss7/include/osmo_util.hrl").
+
+% unmodified original called party number in national format
+-define(IAM_CALLED_DEC_IN,
+	#party_number{nature_of_addr_ind=?ISUP_ADDR_NAT_NATIONAL,
+		      internal_net_num=1,
+		      number_incompl_ind=undefined,
+		      numbering_plan=1,
+		      present_restrict=undefined,
+		      screening_ind=undefined,
+		      phone_number=[9,2,9,9,4,1,9,0,8,7,15]}).
+
+-define(IAM_CALLING_EMPTY_DEC_IN,
+	#party_number{nature_of_addr_ind=?ISUP_ADDR_NAT_NATIONAL,
+		      internal_net_num=undefined,
+		      number_incompl_ind=0,
+		      numbering_plan=1,
+		      present_restrict=1,
+		      screening_ind=3,
+		      phone_number=[]}).
+
+% modified called party number in international format
+-define(IAM_CALLED_DEC_OUT,
+	?IAM_CALLED_DEC_IN#party_number{nature_of_addr_ind=?ISUP_ADDR_NAT_INTERNATIONAL,
+					phone_number=[4,9,9,2,9,9,4,1,9,0,8,7,15]}).
+
+
+
+% IAM message in STP-MSC direction containing national number
+-define(ISUP_IAM_DEC, {isup_msg,1,14, [{conn_ind_nature,16}, {fw_call_ind,24832},
+				      {calling_cat,10}, {transm_medium_req,3},
+				      {?ISUP_PAR_CALLED_P_NUM, ?IAM_CALLED_DEC_IN},
+				      {?ISUP_PAR_CALLING_P_NUM, ?IAM_CALLING_EMPTY_DEC_IN},
+				      {57,{2,<<"1À">>}}, {29,{3,<<144,144,163>>}}]}).
+
+% modified IAM message in STP-MSC direction containing internationalized number
+-define(ISUP_IAM_OUT, {isup_msg,1,14, [{conn_ind_nature,16}, {fw_call_ind,24832},
+				      {calling_cat,10}, {transm_medium_req,3},
+				      {?ISUP_PAR_CALLED_P_NUM, ?IAM_CALLED_DEC_OUT},
+				      {?ISUP_PAR_CALLING_P_NUM, ?IAM_CALLING_EMPTY_DEC_IN},
+				      {57,{2,<<"1À">>}}, {29,{3,<<144,144,163>>}}]}).
+
+
+% variant: calling number is national number with 00 prefix, need to
+% remove 00 and set to international
+-define(IAM_CALLING00_DEC_IN,
+	?IAM_CALLING_EMPTY_DEC_IN#party_number{phone_number=[0,0,4,9,1,2,3,4,5,6,7,8,9,0,15]}).
+-define(IAM_CALLING00_DEC_OUT,
+	?IAM_CALLING00_DEC_IN#party_number{nature_of_addr_ind=?ISUP_ADDR_NAT_INTERNATIONAL,
+					   phone_number=[4,9,1,2,3,4,5,6,7,8,9,0,15]}).
+-define(ISUP_IAM00_DEC, {isup_msg,1,14, [{conn_ind_nature,16}, {fw_call_ind,24832},
+				      {calling_cat,10}, {transm_medium_req,3},
+				      {?ISUP_PAR_CALLED_P_NUM, ?IAM_CALLED_DEC_IN},
+				      {?ISUP_PAR_CALLING_P_NUM, ?IAM_CALLING00_DEC_IN},
+				      {57,{2,<<"1À">>}}, {29,{3,<<144,144,163>>}}]}).
+-define(ISUP_IAM00_OUT, {isup_msg,1,14, [{conn_ind_nature,16}, {fw_call_ind,24832},
+				      {calling_cat,10}, {transm_medium_req,3},
+				      {?ISUP_PAR_CALLED_P_NUM, ?IAM_CALLED_DEC_OUT},
+				      {?ISUP_PAR_CALLING_P_NUM, ?IAM_CALLING00_DEC_OUT},
+				      {57,{2,<<"1À">>}}, {29,{3,<<144,144,163>>}}]}).
+
+setup() ->
+	application:set_env(mgw_nat, msrn_pfx_msc, 41489099),
+	application:set_env(mgw_nat, msrn_pfx_stp, 4991806040),
+	application:set_env(mgw_nat, intern_pfx, 49).
+	%mgw_nat_act_vfuk_onw:reload_config().
+
+teardown(_) ->
+	application:unset_env(mgw_nat, msrn_pfx_msc),
+	application:unset_env(mgw_nat, msrn_pfx_stp),
+	application:unset_env(mgw_nat, intenr_pfx).
+
+
+mangle_rx_iam() ->
+	?assertEqual(?ISUP_IAM_OUT, mgw_nat:mangle_rx_isup(from_stp, path, 1, ?ISUP_IAM_DEC)).
+
+mangle_rx_iam00() ->
+	?assertEqual(?ISUP_IAM00_OUT, mgw_nat:mangle_rx_isup(from_stp, path, 1, ?ISUP_IAM00_DEC)).
+
+bow_onw_test_() ->
+	{setup,
+		fun setup/0,
+		fun teardown/1,
+		[ ?_test(mangle_rx_iam()),
+	          ?_test(mangle_rx_iam00())
+		]
+	}.