diff --git a/drivers/bluetooth/hci/userchan.c b/drivers/bluetooth/hci/userchan.c
index 26fb4668b0e..275ab5d29e2 100644
--- a/drivers/bluetooth/hci/userchan.c
+++ b/drivers/bluetooth/hci/userchan.c
@@ -106,7 +106,7 @@ static void rx_thread(void *p1, void *p2, void *p3)
 		ssize_t len;
 
 		if (!uc_ready()) {
-			k_sleep(K_MSEC(20));
+			k_sleep(K_MSEC(1));
 			continue;
 		}
 
diff --git a/tests/bluetooth/shell/boards/native_posix.conf b/tests/bluetooth/shell/boards/native_posix.conf
new file mode 100644
index 00000000000..e52a0a2849b
--- /dev/null
+++ b/tests/bluetooth/shell/boards/native_posix.conf
@@ -0,0 +1,9 @@
+CONFIG_NO_OPTIMIZATIONS=y
+# Allows for copying larger amount of data into the shell
+CONFIG_SHELL_BACKEND_SERIAL_RX_RING_BUFFER_SIZE=4096
+
+# For native posix k_sleep is used in the data path as well as for shell input
+# detection, hence data processing is at least two ticks per packet. To support
+# 5ms ISO interval bidirectional data the system shall never stall for more
+# than 1.5 ms in average.
+CONFIG_SYS_CLOCK_TICKS_PER_SEC=500
diff --git a/tests/bluetooth/shell/prj.conf b/tests/bluetooth/shell/prj.conf
index 4fe7ea05d53..1767e51a188 100644
--- a/tests/bluetooth/shell/prj.conf
+++ b/tests/bluetooth/shell/prj.conf
@@ -50,7 +50,7 @@ CONFIG_BT_AUTO_PHY_UPDATE=y
 CONFIG_BT_AUDIO=y
 CONFIG_BT_AUDIO_UNICAST=y
 CONFIG_BT_AUDIO_BROADCAST=y
-
+CONFIG_BT_ISO_TX_BUF_COUNT=5
 CONFIG_BT_VOCS_MAX_INSTANCE_COUNT=1
 CONFIG_BT_VOCS_CLIENT_MAX_INSTANCE_COUNT=1