diff --git a/pyproject.toml b/pyproject.toml
index 00a21e8..eaa2e3d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "sendbee_api"
-version = "1.8.0"
+version = "1.8.1"
 description = "Python client SDK for Sendbee Public API"
 readme = "README.md"
 requires-python = ">=3.6"
@@ -27,7 +27,7 @@ classifiers = [
 dependencies = [
     "click>=7.0",
     "requests>=2.20.0",
-    "dumpit>=0.5.0",
+    "dumpit>=0.6.1",
     "aenum>=2.1.2",
     "ujson>=5.7.0,<6",
     "cryptography>=3.2",
diff --git a/sendbee_api/conversations/models.py b/sendbee_api/conversations/models.py
index 3853093..45c4d84 100644
--- a/sendbee_api/conversations/models.py
+++ b/sendbee_api/conversations/models.py
@@ -52,6 +52,14 @@ class ConversationContact(Model):
     _id = TextField(index='id', desc='UUID')
     _name = TextField(index='name', desc='Name')
     _phone = TextField(index='phone', desc='Phone number')
+    _whatsapp_user_id = TextField(
+        index='whatsapp_user_id', 
+        desc='Business-scoped user ID (BSUID) of the ' \
+            'recipient, e.g. US.13491208655302741918. ' \
+            'Used instead of "to" when the phone number ' \
+            'is unknown. If both "to" and "recipient" ' \
+            'are provided, Meta gives precedence to "to".'
+    )
 
 
 class ConversationLastMessage(Model):
diff --git a/sendbee_api/conversations/query_params.py b/sendbee_api/conversations/query_params.py
index 1ad4597..e5f85cd 100644
--- a/sendbee_api/conversations/query_params.py
+++ b/sendbee_api/conversations/query_params.py
@@ -28,6 +28,11 @@ class SendMessage(QueryParams):
     """Parameters for sending message"""
 
     phone = 'phone', 'Contact\'s phone number'
+    whatsapp_user_id = 'whatsapp_user_id', 'Business-scoped user ID (BSUID) of the ' \
+                                            'recipient, e.g. US.13491208655302741918. ' \
+                                            'Used instead of "to" when the phone number ' \
+                                            'is unknown. If both "to" and "recipient" ' \
+                                            'are provided, Meta gives precedence to "to".'
     text = 'text', 'Message text'
     media_url = 'media_url', 'Media URL for media message'
     prevent_bot_off = 'prevent_bot_off', 'Prevent turning-off chatbot'