diff --git a/ontology/observable/observable.ttl b/ontology/observable/observable.ttl
index a34698b8..4da10400 100644
--- a/ontology/observable/observable.ttl
+++ b/ontology/observable/observable.ttl
@@ -3497,28 +3497,28 @@ observable:MessageFacet
 			sh:path observable:from ;
 		] ,
 		[
-			sh:datatype xsd:dateTime ;
+			sh:datatype xsd:MessageTypeVocab ;
 			sh:maxCount "1"^^xsd:integer ;
 			sh:nodeKind sh:Literal ;
-			sh:path observable:sentTime ;
+			sh:path observable:messageType ;
 		] ,
 		[
-			sh:datatype xsd:string ;
+			sh:datatype xsd:dateTime ;
 			sh:maxCount "1"^^xsd:integer ;
 			sh:nodeKind sh:Literal ;
-			sh:path observable:messageID ;
+			sh:path observable:sentTime ;
 		] ,
 		[
 			sh:datatype xsd:string ;
 			sh:maxCount "1"^^xsd:integer ;
 			sh:nodeKind sh:Literal ;
-			sh:path observable:messageText ;
+			sh:path observable:messageID ;
 		] ,
 		[
 			sh:datatype xsd:string ;
 			sh:maxCount "1"^^xsd:integer ;
 			sh:nodeKind sh:Literal ;
-			sh:path observable:messageType ;
+			sh:path observable:messageText ;
 		] ,
 		[
 			sh:datatype xsd:string ;
@@ -10182,8 +10182,8 @@ observable:messageText
 observable:messageType
 	a owl:DatatypeProperty ;
 	rdfs:label "messageType"@en ;
-	rdfs:comment "Message type specifies what sort of message (email, chat, SMS, etc) a Message is."@en ;
-	rdfs:range xsd:string ;
+	rdfs:comment "Message type specifies what sort of message (Email, Chat, SMS/MMS, etc) a Message is."@en ;
+	rdfs:range vocabulary:MessageTypeVocab ;
 	.
 
 observable:messagingAddress
diff --git a/ontology/vocabulary/vocabulary.ttl b/ontology/vocabulary/vocabulary.ttl
index 83f6e472..f67eb5f1 100644
--- a/ontology/vocabulary/vocabulary.ttl
+++ b/ontology/vocabulary/vocabulary.ttl
@@ -601,6 +601,21 @@ vocabulary:MemoryBlockTypeVocab
 	) ;
 	.
 
+vocabulary:MessageTypeVocab
+	a rdfs:Datatype ;
+	rdfs:subClassOf rdfs:Resource ;
+	rdfs:label "Message Type Vocabulary"@en-US ;
+	rdfs:comment "Defines an open-vocabulary of message types that specify which type of message (email, chat, SMS, etc) a Message is."@en ;
+	owl:oneOf (
+		"SMS/MMS"^^vocabulary:MessageTypeVocab
+		"Email"^^vocabulary:MessageTypeVocab
+		"Chat"^^vocabulary:MessageTypeVocab
+		"Phone"^^vocabulary:MessageTypeVocab
+		"Mail"^^vocabulary:MessageTypeVocab
+		"Human"^^vocabulary:MessageTypeVocab
+	) ;
+	.
+
 vocabulary:ObservableObjectRelationshipVocab
 	a rdfs:Datatype ;
 	rdfs:subClassOf rdfs:Resource ;