diff --git a/sdk/rt/pyproject.toml b/sdk/rt/pyproject.toml
index ab70780..b2d84b1 100644
--- a/sdk/rt/pyproject.toml
+++ b/sdk/rt/pyproject.toml
@@ -10,7 +10,7 @@ readme = "README.md"
 authors = [{ name = "Speechmatics", email = "support@speechmatics.com" }]
 license = "MIT"
 requires-python = ">=3.9"
-dependencies = ["websockets>=10.0"]
+dependencies = ["websockets>=10.0", "typing-extensions>=4.5.0"]
 classifiers = [
     "Development Status :: 4 - Beta",
     "Intended Audience :: Developers",
diff --git a/sdk/rt/speechmatics/rt/__init__.py b/sdk/rt/speechmatics/rt/__init__.py
index 861257e..e8ca1e9 100644
--- a/sdk/rt/speechmatics/rt/__init__.py
+++ b/sdk/rt/speechmatics/rt/__init__.py
@@ -21,6 +21,7 @@
 from ._models import ClientMessageType
 from ._models import ConnectionConfig
 from ._models import ConversationConfig
+from ._models import Model
 from ._models import OperatingPoint
 from ._models import ServerMessageType
 from ._models import SessionInfo
@@ -49,6 +50,7 @@
     "EventEmitter",
     "JWTAuth",
     "Microphone",
+    "Model",
     "OperatingPoint",
     "ServerMessageType",
     "SessionError",
diff --git a/sdk/rt/speechmatics/rt/_models.py b/sdk/rt/speechmatics/rt/_models.py
index b0e9a8e..98bef5b 100644
--- a/sdk/rt/speechmatics/rt/_models.py
+++ b/sdk/rt/speechmatics/rt/_models.py
@@ -8,9 +8,10 @@
 from typing import Any
 from typing import Optional
 from typing import cast
-from warnings import deprecated
 from warnings import warn
 
+from typing_extensions import deprecated
+
 
 class AudioEncoding(str, Enum):
     """
@@ -468,7 +469,10 @@ def to_dict(self) -> dict[str, Any]:
             >>> #     "max_delay": 5.0
             >>> # }
         """
-        return asdict(self, dict_factory=lambda x: {k: v for (k, v) in x if v is not None})
+        result = asdict(self, dict_factory=lambda x: {k: v for (k, v) in x if v is not None})
+        if self.model is _UNSET:
+            result.pop("model", None)
+        return result
 
 
 @dataclass