diff --git a/pubsub/Cargo.toml b/pubsub/Cargo.toml
index 5f986314..5c42f5b0 100644
--- a/pubsub/Cargo.toml
+++ b/pubsub/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "google-cloud-pubsub"
-version = "0.28.0"
+version = "0.28.1"
 authors = ["yoshidan <naohiro.y@gmail.com>"]
 edition = "2021"
 repository = "https://github.com/yoshidan/google-cloud-rust/tree/main/pubsub"
diff --git a/pubsub/src/apiv1/subscriber_client.rs b/pubsub/src/apiv1/subscriber_client.rs
index f1189310..9b70d496 100644
--- a/pubsub/src/apiv1/subscriber_client.rs
+++ b/pubsub/src/apiv1/subscriber_client.rs
@@ -33,13 +33,17 @@ pub(crate) fn create_empty_streaming_pull_request() -> StreamingPullRequest {
 #[derive(Clone, Debug)]
 pub struct SubscriberClient {
     cm: Arc<ConnectionManager>,
+    streaming_pull_cm: Arc<ConnectionManager>,
 }
 
 #[allow(dead_code)]
 impl SubscriberClient {
     /// create new Subscriber client
-    pub fn new(cm: ConnectionManager) -> SubscriberClient {
-        SubscriberClient { cm: Arc::new(cm) }
+    pub fn new(cm: ConnectionManager, streaming_pull_cm: ConnectionManager) -> SubscriberClient {
+        SubscriberClient {
+            cm: Arc::new(cm),
+            streaming_pull_cm: Arc::new(streaming_pull_cm),
+        }
     }
 
     #[inline]
@@ -49,8 +53,15 @@ impl SubscriberClient {
             .max_encoding_message_size(PUBSUB_MESSAGE_LIMIT)
     }
 
-    pub(crate) fn pool_size(&self) -> usize {
-        self.cm.num()
+    #[inline]
+    fn client_for_streaming_pull(&self) -> InternalSubscriberClient<Channel> {
+        InternalSubscriberClient::new(self.streaming_pull_cm.conn())
+            .max_decoding_message_size(PUBSUB_MESSAGE_LIMIT)
+            .max_encoding_message_size(PUBSUB_MESSAGE_LIMIT)
+    }
+
+    pub(crate) fn streaming_pool_size(&self) -> usize {
+        self.streaming_pull_cm.num()
     }
 
     /// create_subscription creates a subscription to a given topic. See the [resource name rules]
@@ -231,7 +242,7 @@ impl SubscriberClient {
         retry: Option<RetrySetting>,
     ) -> Result<Response<Streaming<StreamingPullResponse>>, Status> {
         let action = || async {
-            let mut client = self.client();
+            let mut client = self.client_for_streaming_pull();
             let base_req = req.clone();
             let rx = ping_receiver.clone();
             let request = Box::pin(async_stream::stream! {
diff --git a/pubsub/src/client.rs b/pubsub/src/client.rs
index c0cace61..5cc7303b 100644
--- a/pubsub/src/client.rs
+++ b/pubsub/src/client.rs
@@ -126,8 +126,14 @@ impl Client {
                 &config.connection_option,
             )
             .await?,
+            ConnectionManager::new(
+                pool_size,
+                config.endpoint.as_str(),
+                &config.environment,
+                &config.connection_option,
+            )
+            .await?,
         );
-
         Ok(Self {
             project_id: config.project_id.ok_or(Error::ProjectIdNotFound)?,
             pubc,
diff --git a/pubsub/src/subscriber.rs b/pubsub/src/subscriber.rs
index 390288c5..5a63c5dd 100644
--- a/pubsub/src/subscriber.rs
+++ b/pubsub/src/subscriber.rs
@@ -362,7 +362,7 @@ mod tests {
             .await
             .unwrap()
         };
-        let subc = SubscriberClient::new(cm().await);
+        let subc = SubscriberClient::new(cm().await, cm().await);
         let pubc = PublisherClient::new(cm().await);
 
         pubc.publish(
diff --git a/pubsub/src/subscription.rs b/pubsub/src/subscription.rs
index e256a0d2..f0424ab3 100644
--- a/pubsub/src/subscription.rs
+++ b/pubsub/src/subscription.rs
@@ -211,8 +211,8 @@ impl Subscription {
         Self { fqsn, subc }
     }
 
-    pub(crate) fn pool_size(&self) -> usize {
-        self.subc.pool_size()
+    pub(crate) fn streaming_pool_size(&self) -> usize {
+        self.subc.streaming_pool_size()
     }
 
     /// id returns the unique identifier of the subscription within its project.
@@ -459,7 +459,7 @@ impl Subscription {
 
         // spawn a separate subscriber task for each connection in the pool
         let subscribers = if opt.enable_multiple_subscriber {
-            self.pool_size()
+            self.streaming_pool_size()
         } else {
             1
         };
@@ -649,8 +649,8 @@ impl Subscription {
     /// - The message backlog on the subscription -- or to be specific, messages that are unacknowledged
     ///   at the time of the subscription's creation.
     /// - All messages published to the subscription's topic after the snapshot's creation.
-    /// Snapshots have a finite lifetime -- a maximum of 7 days from the time of creation, beyond which
-    /// they are discarded and any messages being retained solely due to the snapshot dropped.
+    ///   Snapshots have a finite lifetime -- a maximum of 7 days from the time of creation, beyond which
+    ///   they are discarded and any messages being retained solely due to the snapshot dropped.
     pub async fn create_snapshot(
         &self,
         name: &str,
@@ -740,7 +740,15 @@ mod tests {
         )
         .await
         .unwrap();
-        let client = SubscriberClient::new(cm);
+        let cm2 = ConnectionManager::new(
+            4,
+            "",
+            &Environment::Emulator(EMULATOR.to_string()),
+            &ConnectionOptions::default(),
+        )
+        .await
+        .unwrap();
+        let client = SubscriberClient::new(cm, cm2);
 
         let uuid = Uuid::new_v4().hyphenated().to_string();
         let subscription_name = format!("projects/{}/subscriptions/s{}", PROJECT_NAME, &uuid);
diff --git a/pubsub/src/topic.rs b/pubsub/src/topic.rs
index 36757028..55594103 100644
--- a/pubsub/src/topic.rs
+++ b/pubsub/src/topic.rs
@@ -164,7 +164,10 @@ mod tests {
         let cm2 = ConnectionManager::new(4, "", &environment, &ConnectionOptions::default())
             .await
             .unwrap();
-        let subc = SubscriberClient::new(cm2);
+        let cm3 = ConnectionManager::new(4, "", &environment, &ConnectionOptions::default())
+            .await
+            .unwrap();
+        let subc = SubscriberClient::new(cm2, cm3);
 
         let uuid = Uuid::new_v4().hyphenated().to_string();
         let topic_name = format!("projects/local-project/topics/t{uuid}");