diff --git a/include/zephyr/modem/pipe.h b/include/zephyr/modem/pipe.h
index 4fdd98155d..945cace6bb 100644
--- a/include/zephyr/modem/pipe.h
+++ b/include/zephyr/modem/pipe.h
@@ -53,6 +53,7 @@ struct modem_pipe {
 	enum modem_pipe_state state;
 	struct k_mutex lock;
 	struct k_condvar condvar;
+	bool receive_ready_pending;
 };
 
 /**
diff --git a/subsys/modem/modem_pipe.c b/subsys/modem/modem_pipe.c
index ca2a26020b..5240c5ebc2 100644
--- a/subsys/modem/modem_pipe.c
+++ b/subsys/modem/modem_pipe.c
@@ -20,6 +20,7 @@ void modem_pipe_init(struct modem_pipe *pipe, void *data, struct modem_pipe_api
 	pipe->callback = NULL;
 	pipe->user_data = NULL;
 	pipe->state = MODEM_PIPE_STATE_CLOSED;
+	pipe->receive_ready_pending = false;
 
 	k_mutex_init(&pipe->lock);
 	k_condvar_init(&pipe->condvar);
@@ -63,6 +64,11 @@ void modem_pipe_attach(struct modem_pipe *pipe, modem_pipe_api_callback callback
 	k_mutex_lock(&pipe->lock, K_FOREVER);
 	pipe->callback = callback;
 	pipe->user_data = user_data;
+
+	if (pipe->receive_ready_pending && (pipe->callback != NULL)) {
+		pipe->callback(pipe, MODEM_PIPE_EVENT_RECEIVE_READY, pipe->user_data);
+	}
+
 	k_mutex_unlock(&pipe->lock);
 }
 
@@ -94,6 +100,7 @@ int modem_pipe_receive(struct modem_pipe *pipe, uint8_t *buf, size_t size)
 	}
 
 	ret = pipe->api->receive(pipe->data, buf, size);
+	pipe->receive_ready_pending = false;
 	k_mutex_unlock(&pipe->lock);
 	return ret;
 }
@@ -155,6 +162,7 @@ void modem_pipe_notify_closed(struct modem_pipe *pipe)
 {
 	k_mutex_lock(&pipe->lock, K_FOREVER);
 	pipe->state = MODEM_PIPE_STATE_CLOSED;
+	pipe->receive_ready_pending = false;
 
 	if (pipe->callback != NULL) {
 		pipe->callback(pipe, MODEM_PIPE_EVENT_CLOSED, pipe->user_data);
@@ -168,6 +176,8 @@ void modem_pipe_notify_receive_ready(struct modem_pipe *pipe)
 {
 	k_mutex_lock(&pipe->lock, K_FOREVER);
 
+	pipe->receive_ready_pending = true;
+
 	if (pipe->callback != NULL) {
 		pipe->callback(pipe, MODEM_PIPE_EVENT_RECEIVE_READY, pipe->user_data);
 	}
diff --git a/tests/subsys/modem/modem_cmux/src/main.c b/tests/subsys/modem/modem_cmux/src/main.c
index 13422641b9..115b3bd89b 100644
--- a/tests/subsys/modem/modem_cmux/src/main.c
+++ b/tests/subsys/modem/modem_cmux/src/main.c
@@ -265,32 +265,26 @@ static void *test_modem_cmux_setup(void)
 	};
 
 	bus_mock_pipe = modem_backend_mock_init(&bus_mock, &bus_mock_config);
-	__ASSERT_NO_MSG(modem_pipe_open_async(bus_mock_pipe) == 0);
+	__ASSERT_NO_MSG(modem_pipe_open(bus_mock_pipe) == 0);
 
 	/* Connect CMUX */
 	__ASSERT_NO_MSG(modem_cmux_attach(&cmux, bus_mock_pipe) == 0);
+	modem_backend_mock_prime(&bus_mock, &transaction_control_sabm);
 	__ASSERT_NO_MSG(modem_cmux_connect_async(&cmux) == 0);
-	modem_backend_mock_put(&bus_mock, cmux_frame_control_sabm_ack,
-			       sizeof(cmux_frame_control_sabm_ack));
-
 	events = k_event_wait(&cmux_event, EVENT_CMUX_CONNECTED, false, K_MSEC(100));
 	__ASSERT_NO_MSG(events == EVENT_CMUX_CONNECTED);
 
 	/* Open DLCI channels */
 	modem_pipe_attach(dlci1_pipe, test_modem_dlci1_pipe_callback, NULL);
-	modem_pipe_attach(dlci2_pipe, test_modem_dlci2_pipe_callback, NULL);
+	modem_backend_mock_prime(&bus_mock, &transaction_dlci1_sabm);
 	__ASSERT_NO_MSG(modem_pipe_open_async(dlci1_pipe) == 0);
-	__ASSERT_NO_MSG(modem_pipe_open_async(dlci2_pipe) == 0);
-	modem_backend_mock_put(&bus_mock, cmux_frame_dlci1_sabm_ack,
-			       sizeof(cmux_frame_dlci1_sabm_ack));
-
-	modem_backend_mock_put(&bus_mock, cmux_frame_dlci2_sabm_ack,
-			       sizeof(cmux_frame_dlci2_sabm_ack));
-
-	events = k_event_wait_all(&cmux_event, (EVENT_CMUX_DLCI1_OPEN | EVENT_CMUX_DLCI2_OPEN),
-				  false, K_MSEC(100));
-
+	events = k_event_wait(&cmux_event, EVENT_CMUX_DLCI1_OPEN, false, K_MSEC(100));
 	__ASSERT_NO_MSG((events & EVENT_CMUX_DLCI1_OPEN));
+
+	modem_pipe_attach(dlci2_pipe, test_modem_dlci2_pipe_callback, NULL);
+	modem_backend_mock_prime(&bus_mock, &transaction_dlci2_sabm);
+	__ASSERT_NO_MSG(modem_pipe_open_async(dlci2_pipe) == 0);
+	events = k_event_wait(&cmux_event, EVENT_CMUX_DLCI2_OPEN, false, K_MSEC(100));
 	__ASSERT_NO_MSG((events & EVENT_CMUX_DLCI2_OPEN));
 
 	return NULL;