diff --git a/CHANGELOG.md b/CHANGELOG.md
index 44baae1131..21cbd4c1bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,8 @@ release.
   ([#317](https://github.com/open-telemetry/semantic-conventions/pull/317))
 - BREAKING: Change type of `host.cpu.model.id` and `host.cpu.model.family` to string.
   ([#495](https://github.com/open-telemetry/semantic-conventions/issues/495))
+- Changed `messaging.system` attribute type to an open enum
+  ([#517](https://github.com/open-telemetry/semantic-conventions/pull/517))
 
 ### Features
 
diff --git a/docs/attributes-registry/messaging.md b/docs/attributes-registry/messaging.md
index 27bbae84c4..fe5523c85d 100644
--- a/docs/attributes-registry/messaging.md
+++ b/docs/attributes-registry/messaging.md
@@ -36,7 +36,7 @@
 | `messaging.rocketmq.message.tag` | string | The secondary classifier of message besides topic. | `tagA` |
 | `messaging.rocketmq.message.type` | string | Type of message. | `normal` |
 | `messaging.rocketmq.namespace` | string | Namespace of RocketMQ resources, resources in different namespaces are individual. | `myNamespace` |
-| `messaging.system` | string | A string identifying the messaging system. | `kafka`; `rabbitmq`; `rocketmq`; `activemq` |
+| `messaging.system` | string | An identifier for the messaging system being used. See below for a list of well-known identifiers. | `activemq` |
 
 **[1]:** Instrumentations SHOULD NOT set `messaging.batch.message_count` on spans that operate with a single message. When a messaging client library supports both batch and single-message API for the same operation, instrumentations SHOULD use `messaging.batch.message_count` for batching APIs and SHOULD NOT use it for single-message APIs.
 
@@ -82,4 +82,19 @@ size should be used.
 | `fifo` | FIFO message |
 | `delay` | Delay message |
 | `transaction` | Transaction message |
+
+`messaging.system` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `activemq` | Apache ActiveMQ |
+| `aws_sqs` | Amazon Simple Queue Service (SQS) |
+| `azure_eventgrid` | Azure Event Grid |
+| `azure_eventhubs` | Azure Event Hubs |
+| `azure_servicebus` | Azure Service Bus |
+| `gcp_pubsub` | Google Cloud Pub/Sub |
+| `jms` | Java Message Service |
+| `kafka` | Apache Kafka |
+| `rabbitmq` | RabbitMQ |
+| `rocketmq` | Apache RocketMQ |
 <!-- endsemconv -->
diff --git a/docs/messaging/messaging-spans.md b/docs/messaging/messaging-spans.md
index fa95e8c3b2..19cfbc43e1 100644
--- a/docs/messaging/messaging-spans.md
+++ b/docs/messaging/messaging-spans.md
@@ -287,7 +287,7 @@ messages were received). For each message it accounts for, the "Deliver" or
 | [`messaging.message.envelope.size`](../attributes-registry/messaging.md) | int | The size of the message body and metadata in bytes. [12] | `2738` | Recommended: [13] |
 | [`messaging.message.id`](../attributes-registry/messaging.md) | string | A value used by the messaging system as an identifier for the message, represented as a string. | `452a7c7c7c7048c2f887f61572b18fc2` | Recommended: [14] |
 | [`messaging.operation`](../attributes-registry/messaging.md) | string | A string identifying the kind of messaging operation. [15] | `publish` | Required |
-| [`messaging.system`](../attributes-registry/messaging.md) | string | A string identifying the messaging system. | `kafka`; `rabbitmq`; `rocketmq`; `activemq` | Required |
+| [`messaging.system`](../attributes-registry/messaging.md) | string | An identifier for the messaging system being used. See below for a list of well-known identifiers. | `activemq` | Required |
 | [`network.peer.address`](../attributes-registry/network.md) | string | Peer address of the network connection - IP address or Unix domain socket name. | `10.1.2.80`; `/tmp/my.sock` | Recommended |
 | [`network.peer.port`](../attributes-registry/network.md) | int | Peer port number of the network connection. | `65123` | Recommended: If `network.peer.address` is set. |
 | [`network.protocol.name`](../attributes-registry/network.md) | string | [OSI application layer](https://osi-model.com/application-layer/) or non-OSI equivalent. [16] | `amqp`; `mqtt` | Recommended |
@@ -352,6 +352,21 @@ different processes could be listening on TCP port 12345 and UDP port 12345.
 | `receive` | One or more messages are requested by a consumer. This operation refers to pull-based scenarios, where consumers explicitly call methods of messaging SDKs to receive messages. |
 | `deliver` | One or more messages are passed to a consumer. This operation refers to push-based scenarios, where consumer register callbacks which get called by messaging SDKs. |
 
+`messaging.system` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `activemq` | Apache ActiveMQ |
+| `aws_sqs` | Amazon Simple Queue Service (SQS) |
+| `azure_eventgrid` | Azure Event Grid |
+| `azure_eventhubs` | Azure Event Hubs |
+| `azure_servicebus` | Azure Service Bus |
+| `gcp_pubsub` | Google Cloud Pub/Sub |
+| `jms` | Java Message Service |
+| `kafka` | Apache Kafka |
+| `rabbitmq` | RabbitMQ |
+| `rocketmq` | Apache RocketMQ |
+
 `network.transport` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
 
 | Value  | Description |
diff --git a/model/registry/messaging.yaml b/model/registry/messaging.yaml
index f7dd6257ab..64dc6fe5a0 100644
--- a/model/registry/messaging.yaml
+++ b/model/registry/messaging.yaml
@@ -203,6 +203,38 @@ groups:
           Namespace of RocketMQ resources, resources in different namespaces are individual.
         examples: 'myNamespace'
       - id: system
-        type: string
-        brief: 'A string identifying the messaging system.'
-        examples: ['kafka', 'rabbitmq', 'rocketmq', 'activemq']
+        brief: >
+          An identifier for the messaging system being used. See below for a list of well-known identifiers.
+        type:
+          allow_custom_values: true
+          members:
+            - id: activemq
+              value: 'activemq'
+              brief: 'Apache ActiveMQ'
+            - id: aws_sqs
+              value: 'aws_sqs'
+              brief: 'Amazon Simple Queue Service (SQS)'
+            - id: azure_eventgrid
+              value: 'azure_eventgrid'
+              brief: 'Azure Event Grid'
+            - id: azure_eventhubs
+              value: 'azure_eventhubs'
+              brief: 'Azure Event Hubs'
+            - id: azure_servicebus
+              value: 'azure_servicebus'
+              brief: 'Azure Service Bus'
+            - id: gcp_pubsub
+              value: 'gcp_pubsub'
+              brief: 'Google Cloud Pub/Sub'
+            - id: jms
+              value: 'jms'
+              brief: 'Java Message Service'
+            - id: kafka
+              value: 'kafka'
+              brief: 'Apache Kafka'
+            - id: rabbitmq
+              value: 'rabbitmq'
+              brief: 'RabbitMQ'
+            - id: rocketmq
+              value: 'rocketmq'
+              brief: 'Apache RocketMQ'