consistently use 0-based counting of modems/slots
diff --git a/firmware/libboard/common/source/sim_switch.c b/firmware/libboard/common/source/sim_switch.c
index 49e6cea..598cd4d 100644
--- a/firmware/libboard/common/source/sim_switch.c
+++ b/firmware/libboard/common/source/sim_switch.c
@@ -27,12 +27,12 @@
 
 	switch (nr) {
 #ifdef PIN_SIM_SWITCH1
-	case 1:
+	case 0:
 		pin = &pin_conn_usim1;
 		break;
 #endif
 #ifdef PIN_SIM_SWITCH2
-	case 2:
+	case 1:
 		pin = &pin_conn_usim2;
 		break;
 #endif
diff --git a/firmware/libboard/qmod/source/board_qmod.c b/firmware/libboard/qmod/source/board_qmod.c
index 54983d7..d14c29c 100644
--- a/firmware/libboard/qmod/source/board_qmod.c
+++ b/firmware/libboard/qmod/source/board_qmod.c
@@ -184,17 +184,17 @@
 		break;
 	case '1':
 		printf("Resetting Modem 1 (of this SAM3)\n\r");
-		wwan_perst_do_reset_pulse(1, 300);
+		wwan_perst_do_reset_pulse(0, 300);
 		break;
 	case '2':
 		printf("Resetting Modem 2 (of this SAM3)\n\r");
-		wwan_perst_do_reset_pulse(2, 300);
+		wwan_perst_do_reset_pulse(1, 300);
 		break;
 	case '!':
-		sim_switch_use_physical(1, 0);
+		sim_switch_use_physical(0, 0);
 		break;
 	case '@':
-		sim_switch_use_physical(2, 0);
+		sim_switch_use_physical(0, 0);
 		break;
 	default:
 		if (!qmod_sam3_is_12())
diff --git a/firmware/libboard/qmod/source/wwan_perst.c b/firmware/libboard/qmod/source/wwan_perst.c
index f16006f..b80fd55 100644
--- a/firmware/libboard/qmod/source/wwan_perst.c
+++ b/firmware/libboard/qmod/source/wwan_perst.c
@@ -45,11 +45,11 @@
 
 	switch (modem_nr) {
 #ifdef PIN_PERST1
-	case 1:
+	case 0:
 		return &perst1;
 #endif
 #ifdef PIN_PERST2
-	case 2:
+	case 1:
 		return &perst2;
 #endif
 	default: