diff --git a/src/bluetooth.c b/src/bluetooth.c
index b55bf86..088d027 100644
--- a/src/bluetooth.c
+++ b/src/bluetooth.c
@@ -99,18 +99,18 @@ static const dc_iterator_vtable_t dc_bluetooth_iterator_vtable = {
 static const dc_iostream_vtable_t dc_bluetooth_vtable = {
 	sizeof(dc_socket_t),
 	dc_socket_set_timeout, /* set_timeout */
-	dc_socket_set_latency, /* set_latency */
-	dc_socket_set_break, /* set_break */
-	dc_socket_set_dtr, /* set_dtr */
-	dc_socket_set_rts, /* set_rts */
-	dc_socket_get_lines, /* get_lines */
-	dc_socket_get_available, /* get_received */
-	dc_socket_configure, /* configure */
+	NULL, /* set_latency */
+	NULL, /* set_break */
+	NULL, /* set_dtr */
+	NULL, /* set_rts */
+	NULL, /* get_lines */
+	dc_socket_get_available, /* get_available */
+	NULL, /* configure */
 	dc_socket_read, /* read */
 	dc_socket_write, /* write */
-	dc_socket_flush, /* flush */
-	dc_socket_purge, /* purge */
-	dc_socket_sleep, /* sleep */
+	NULL, /* flush */
+	NULL, /* purge */
+	NULL, /* sleep */
 	dc_socket_close, /* close */
 };
 
diff --git a/src/custom.c b/src/custom.c
index 1e03aa7..8db276b 100644
--- a/src/custom.c
+++ b/src/custom.c
@@ -58,7 +58,7 @@ static const dc_iostream_vtable_t dc_custom_vtable = {
 	dc_custom_set_dtr, /* set_dtr */
 	dc_custom_set_rts, /* set_rts */
 	dc_custom_get_lines, /* get_lines */
-	dc_custom_get_available, /* get_received */
+	dc_custom_get_available, /* get_available */
 	dc_custom_configure, /* configure */
 	dc_custom_read, /* read */
 	dc_custom_write, /* write */
@@ -99,7 +99,7 @@ dc_custom_set_timeout (dc_iostream_t *abstract, int timeout)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.set_timeout == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.set_timeout (custom->userdata, timeout);
 }
@@ -110,7 +110,7 @@ dc_custom_set_latency (dc_iostream_t *abstract, unsigned int value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.set_latency == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.set_latency (custom->userdata, value);
 }
@@ -121,7 +121,7 @@ dc_custom_set_break (dc_iostream_t *abstract, unsigned int value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.set_break == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.set_break (custom->userdata, value);
 }
@@ -132,7 +132,7 @@ dc_custom_set_dtr (dc_iostream_t *abstract, unsigned int value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.set_dtr == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.set_dtr (custom->userdata, value);
 }
@@ -143,7 +143,7 @@ dc_custom_set_rts (dc_iostream_t *abstract, unsigned int value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.set_rts == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.set_rts (custom->userdata, value);
 }
@@ -154,7 +154,7 @@ dc_custom_get_lines (dc_iostream_t *abstract, unsigned int *value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.get_lines == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.get_lines (custom->userdata, value);
 }
@@ -165,7 +165,7 @@ dc_custom_get_available (dc_iostream_t *abstract, size_t *value)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.get_available == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.get_available (custom->userdata, value);
 }
@@ -176,7 +176,7 @@ dc_custom_configure (dc_iostream_t *abstract, unsigned int baudrate, unsigned in
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.configure == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.configure (custom->userdata, baudrate, databits, parity, stopbits, flowcontrol);
 }
@@ -187,7 +187,7 @@ dc_custom_read (dc_iostream_t *abstract, void *data, size_t size, size_t *actual
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.read == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.read (custom->userdata, data, size, actual);
 }
@@ -198,7 +198,7 @@ dc_custom_write (dc_iostream_t *abstract, const void *data, size_t size, size_t
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.write == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.write (custom->userdata, data, size, actual);
 }
@@ -209,7 +209,7 @@ dc_custom_flush (dc_iostream_t *abstract)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.flush == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.flush (custom->userdata);
 }
@@ -220,7 +220,7 @@ dc_custom_purge (dc_iostream_t *abstract, dc_direction_t direction)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.purge == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.purge (custom->userdata, direction);
 }
@@ -231,7 +231,7 @@ dc_custom_sleep (dc_iostream_t *abstract, unsigned int milliseconds)
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
 	if (custom->callbacks.sleep == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	return custom->callbacks.sleep (custom->userdata, milliseconds);
 }
@@ -239,12 +239,10 @@ dc_custom_sleep (dc_iostream_t *abstract, unsigned int milliseconds)
 static dc_status_t
 dc_custom_close (dc_iostream_t *abstract)
 {
-	dc_status_t status = DC_STATUS_SUCCESS;
 	dc_custom_t *custom = (dc_custom_t *) abstract;
 
-	if (custom->callbacks.close) {
-		status = custom->callbacks.close (custom->userdata);
-	}
+	if (custom->callbacks.close == NULL)
+		return DC_STATUS_SUCCESS;
 
-	return status;
+	return custom->callbacks.close (custom->userdata);
 }
diff --git a/src/iostream.c b/src/iostream.c
index 9681d02..e0ba7fc 100644
--- a/src/iostream.c
+++ b/src/iostream.c
@@ -25,6 +25,7 @@
 
 #include "iostream-private.h"
 #include "context-private.h"
+#include "platform.h"
 
 dc_iostream_t *
 dc_iostream_allocate (dc_context_t *context, const dc_iostream_vtable_t *vtable, dc_transport_t transport)
@@ -77,7 +78,7 @@ dc_status_t
 dc_iostream_set_timeout (dc_iostream_t *iostream, int timeout)
 {
 	if (iostream == NULL || iostream->vtable->set_timeout == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Timeout: value=%i", timeout);
 
@@ -88,7 +89,7 @@ dc_status_t
 dc_iostream_set_latency (dc_iostream_t *iostream, unsigned int value)
 {
 	if (iostream == NULL || iostream->vtable->set_latency == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Latency: value=%i", value);
 
@@ -99,7 +100,7 @@ dc_status_t
 dc_iostream_set_break (dc_iostream_t *iostream, unsigned int value)
 {
 	if (iostream == NULL || iostream->vtable->set_break == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Break: value=%i", value);
 
@@ -110,7 +111,7 @@ dc_status_t
 dc_iostream_set_dtr (dc_iostream_t *iostream, unsigned int value)
 {
 	if (iostream == NULL || iostream->vtable->set_dtr == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "DTR: value=%i", value);
 
@@ -121,7 +122,7 @@ dc_status_t
 dc_iostream_set_rts (dc_iostream_t *iostream, unsigned int value)
 {
 	if (iostream == NULL || iostream->vtable->set_rts == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "RTS: value=%i", value);
 
@@ -131,26 +132,50 @@ dc_iostream_set_rts (dc_iostream_t *iostream, unsigned int value)
 dc_status_t
 dc_iostream_get_lines (dc_iostream_t *iostream, unsigned int *value)
 {
-	if (iostream == NULL || iostream->vtable->get_lines == NULL)
-		return DC_STATUS_UNSUPPORTED;
+	dc_status_t status = DC_STATUS_SUCCESS;
+	unsigned int lines = 0;
 
-	return iostream->vtable->get_lines (iostream, value);
+	if (iostream == NULL || iostream->vtable->get_lines == NULL) {
+		goto out;
+	}
+
+	status = iostream->vtable->get_lines (iostream, &lines);
+
+	INFO (iostream->context, "Lines: value=%u", lines);
+
+out:
+	if (value)
+		*value = lines;
+
+	return status;
 }
 
 dc_status_t
 dc_iostream_get_available (dc_iostream_t *iostream, size_t *value)
 {
-	if (iostream == NULL || iostream->vtable->get_available == NULL)
-		return DC_STATUS_UNSUPPORTED;
+	dc_status_t status = DC_STATUS_SUCCESS;
+	size_t available = 0;
 
-	return iostream->vtable->get_available (iostream, value);
+	if (iostream == NULL || iostream->vtable->get_available == NULL) {
+		goto out;
+	}
+
+	status = iostream->vtable->get_available (iostream, &available);
+
+	INFO (iostream->context, "Available: value=" DC_PRINTF_SIZE, available);
+
+out:
+	if (value)
+		*value = available;
+
+	return status;
 }
 
 dc_status_t
 dc_iostream_configure (dc_iostream_t *iostream, unsigned int baudrate, unsigned int databits, dc_parity_t parity, dc_stopbits_t stopbits, dc_flowcontrol_t flowcontrol)
 {
 	if (iostream == NULL || iostream->vtable->configure == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Configure: baudrate=%i, databits=%i, parity=%i, stopbits=%i, flowcontrol=%i",
 		baudrate, databits, parity, stopbits, flowcontrol);
@@ -165,7 +190,6 @@ dc_iostream_read (dc_iostream_t *iostream, void *data, size_t size, size_t *actu
 	size_t nbytes = 0;
 
 	if (iostream == NULL || iostream->vtable->read == NULL) {
-		status = DC_STATUS_UNSUPPORTED;
 		goto out;
 	}
 
@@ -187,7 +211,6 @@ dc_iostream_write (dc_iostream_t *iostream, const void *data, size_t size, size_
 	size_t nbytes = 0;
 
 	if (iostream == NULL || iostream->vtable->read == NULL) {
-		status = DC_STATUS_UNSUPPORTED;
 		goto out;
 	}
 
@@ -206,7 +229,7 @@ dc_status_t
 dc_iostream_flush (dc_iostream_t *iostream)
 {
 	if (iostream == NULL || iostream->vtable->flush == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Flush: none");
 
@@ -217,7 +240,7 @@ dc_status_t
 dc_iostream_purge (dc_iostream_t *iostream, dc_direction_t direction)
 {
 	if (iostream == NULL || iostream->vtable->purge == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Purge: direction=%u", direction);
 
@@ -228,7 +251,7 @@ dc_status_t
 dc_iostream_sleep (dc_iostream_t *iostream, unsigned int milliseconds)
 {
 	if (iostream == NULL || iostream->vtable->sleep == NULL)
-		return DC_STATUS_UNSUPPORTED;
+		return DC_STATUS_SUCCESS;
 
 	INFO (iostream->context, "Sleep: value=%u", milliseconds);
 
diff --git a/src/irda.c b/src/irda.c
index a5cf803..eedb703 100644
--- a/src/irda.c
+++ b/src/irda.c
@@ -91,18 +91,18 @@ static const dc_iterator_vtable_t dc_irda_iterator_vtable = {
 static const dc_iostream_vtable_t dc_irda_vtable = {
 	sizeof(dc_socket_t),
 	dc_socket_set_timeout, /* set_timeout */
-	dc_socket_set_latency, /* set_latency */
-	dc_socket_set_break, /* set_break */
-	dc_socket_set_dtr, /* set_dtr */
-	dc_socket_set_rts, /* set_rts */
-	dc_socket_get_lines, /* get_lines */
-	dc_socket_get_available, /* get_received */
-	dc_socket_configure, /* configure */
+	NULL, /* set_latency */
+	NULL, /* set_break */
+	NULL, /* set_dtr */
+	NULL, /* set_rts */
+	NULL, /* get_lines */
+	dc_socket_get_available, /* get_available */
+	NULL, /* configure */
 	dc_socket_read, /* read */
 	dc_socket_write, /* write */
-	dc_socket_flush, /* flush */
-	dc_socket_purge, /* purge */
-	dc_socket_sleep, /* sleep */
+	NULL, /* flush */
+	NULL, /* purge */
+	NULL, /* sleep */
 	dc_socket_close, /* close */
 };
 #endif
diff --git a/src/serial_posix.c b/src/serial_posix.c
index ff954ef..46ec3de 100644
--- a/src/serial_posix.c
+++ b/src/serial_posix.c
@@ -121,7 +121,7 @@ static const dc_iostream_vtable_t dc_serial_vtable = {
 	dc_serial_set_dtr, /* set_dtr */
 	dc_serial_set_rts, /* set_rts */
 	dc_serial_get_lines, /* get_lines */
-	dc_serial_get_available, /* get_received */
+	dc_serial_get_available, /* get_available */
 	dc_serial_configure, /* configure */
 	dc_serial_read, /* read */
 	dc_serial_write, /* write */
diff --git a/src/serial_win32.c b/src/serial_win32.c
index ff52b41..124857a 100644
--- a/src/serial_win32.c
+++ b/src/serial_win32.c
@@ -91,7 +91,7 @@ static const dc_iostream_vtable_t dc_serial_vtable = {
 	dc_serial_set_dtr, /* set_dtr */
 	dc_serial_set_rts, /* set_rts */
 	dc_serial_get_lines, /* get_lines */
-	dc_serial_get_available, /* get_received */
+	dc_serial_get_available, /* get_available */
 	dc_serial_configure, /* configure */
 	dc_serial_read, /* read */
 	dc_serial_write, /* write */
diff --git a/src/socket.c b/src/socket.c
index 1842a75..948aa46 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -163,39 +163,6 @@ dc_socket_set_timeout (dc_iostream_t *abstract, int timeout)
 	return DC_STATUS_SUCCESS;
 }
 
-dc_status_t
-dc_socket_set_latency (dc_iostream_t *iostream, unsigned int value)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_set_break (dc_iostream_t *iostream, unsigned int value)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_set_dtr (dc_iostream_t *iostream, unsigned int value)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_set_rts (dc_iostream_t *iostream, unsigned int value)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_get_lines (dc_iostream_t *iostream, unsigned int *value)
-{
-	if (value)
-		*value = 0;
-
-	return DC_STATUS_SUCCESS;
-}
-
 dc_status_t
 dc_socket_get_available (dc_iostream_t *abstract, size_t *value)
 {
@@ -219,12 +186,6 @@ dc_socket_get_available (dc_iostream_t *abstract, size_t *value)
 	return DC_STATUS_SUCCESS;
 }
 
-dc_status_t
-dc_socket_configure (dc_iostream_t *abstract, unsigned int baudrate, unsigned int databits, dc_parity_t parity, dc_stopbits_t stopbits, dc_flowcontrol_t flowcontrol)
-{
-	return DC_STATUS_SUCCESS;
-}
-
 dc_status_t
 dc_socket_read (dc_iostream_t *abstract, void *data, size_t size, size_t *actual)
 {
@@ -332,21 +293,3 @@ out:
 
 	return status;
 }
-
-dc_status_t
-dc_socket_flush (dc_iostream_t *abstract)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_purge (dc_iostream_t *abstract, dc_direction_t direction)
-{
-	return DC_STATUS_SUCCESS;
-}
-
-dc_status_t
-dc_socket_sleep (dc_iostream_t *abstract, unsigned int timeout)
-{
-	return DC_STATUS_SUCCESS;
-}
diff --git a/src/socket.h b/src/socket.h
index 626003c..5f5421d 100644
--- a/src/socket.h
+++ b/src/socket.h
@@ -104,42 +104,15 @@ dc_socket_connect (dc_iostream_t *iostream, const struct sockaddr *addr, s_sockl
 dc_status_t
 dc_socket_set_timeout (dc_iostream_t *iostream, int timeout);
 
-dc_status_t
-dc_socket_set_latency (dc_iostream_t *iostream, unsigned int value);
-
-dc_status_t
-dc_socket_set_break (dc_iostream_t *iostream, unsigned int value);
-
-dc_status_t
-dc_socket_set_dtr (dc_iostream_t *iostream, unsigned int value);
-
-dc_status_t
-dc_socket_set_rts (dc_iostream_t *iostream, unsigned int value);
-
-dc_status_t
-dc_socket_get_lines (dc_iostream_t *iostream, unsigned int *value);
-
 dc_status_t
 dc_socket_get_available (dc_iostream_t *iostream, size_t *value);
 
-dc_status_t
-dc_socket_configure (dc_iostream_t *iostream, unsigned int baudrate, unsigned int databits, dc_parity_t parity, dc_stopbits_t stopbits, dc_flowcontrol_t flowcontrol);
-
 dc_status_t
 dc_socket_read (dc_iostream_t *iostream, void *data, size_t size, size_t *actual);
 
 dc_status_t
 dc_socket_write (dc_iostream_t *iostream, const void *data, size_t size, size_t *actual);
 
-dc_status_t
-dc_socket_flush (dc_iostream_t *iostream);
-
-dc_status_t
-dc_socket_purge (dc_iostream_t *iostream, dc_direction_t direction);
-
-dc_status_t
-dc_socket_sleep (dc_iostream_t *iostream, unsigned int milliseconds);
-
 dc_status_t
 dc_socket_close (dc_iostream_t *iostream);
 
diff --git a/src/usbhid.c b/src/usbhid.c
index 0338bfe..a3ddc74 100644
--- a/src/usbhid.c
+++ b/src/usbhid.c
@@ -142,7 +142,7 @@ static const dc_iostream_vtable_t dc_usbhid_vtable = {
 	NULL, /* set_dtr */
 	NULL, /* set_rts */
 	NULL, /* get_lines */
-	NULL, /* get_received */
+	NULL, /* get_available */
 	NULL, /* configure */
 	dc_usbhid_read, /* read */
 	dc_usbhid_write, /* write */