diff --git a/bandwidth.yml b/bandwidth.yml
index 5b874eeb..84e00b33 100644
--- a/bandwidth.yml
+++ b/bandwidth.yml
@@ -5759,6 +5759,19 @@ components:
           items:
             type: string
             pattern: ^\+[1-9]\d{1,14}$
+        rcsAgent:
+          type: string
+          description: >-
+            Override the default RCS sender/agent ID used when checking RCS
+            capabilities.
+
+            When provided, this value is used as the `sender` in the RCS
+            capability-check request instead of the account default.
+
+            Must be 1–40 characters and contain only letters, digits,
+            underscores, or hyphens.
+          pattern: ^[A-Za-z0-9_-]{1,40}$
+          example: MyCustomRcsAgent
       required:
         - phoneNumbers
     asyncLookupRequest:
@@ -8758,6 +8771,13 @@ components:
         phoneNumbers:
           - '+19196104423'
           - '+19196104424'
+    rcsAgentRequestExample:
+      summary: Number Lookup Request with Custom RCS Agent
+      value:
+        phoneNumbers:
+          - '+19196104423'
+          - '+19196104424'
+        rcsAgent: MyCustomRcsAgent
     lookupAcceptedExample:
       summary: Numbers Lookup Accepted
       value:
@@ -9518,6 +9538,8 @@ components:
               $ref: '#/components/examples/singleNumberRequestExample'
             multipleNumberRequestExample:
               $ref: '#/components/examples/multipleNumberRequestExample'
+            rcsAgentRequestExample:
+              $ref: '#/components/examples/rcsAgentRequestExample'
     createAsyncBulkLookupRequest:
       description: Asynchronous bulk phone number lookup request.
       required: true
diff --git a/bandwidth/models/sync_lookup_request.py b/bandwidth/models/sync_lookup_request.py
index 1532a912..dcb30f42 100644
--- a/bandwidth/models/sync_lookup_request.py
+++ b/bandwidth/models/sync_lookup_request.py
@@ -19,7 +19,7 @@
 import json
 
 from pydantic import BaseModel, ConfigDict, Field, field_validator
-from typing import Any, ClassVar, Dict, List
+from typing import Any, ClassVar, Dict, List, Optional
 from typing_extensions import Annotated
 from typing import Optional, Set
 from typing_extensions import Self
@@ -29,8 +29,19 @@ class SyncLookupRequest(BaseModel):
     SyncLookupRequest
     """ # noqa: E501
     phone_numbers: List[Annotated[str, Field(strict=True)]] = Field(description="Telephone numbers in E.164 format.", alias="phoneNumbers")
+    rcs_agent: Optional[Annotated[str, Field(strict=True)]] = Field(default=None, description="Override the default RCS sender/agent ID used when checking RCS capabilities. When provided, this value is used as the `sender` in the RCS capability-check request instead of the account default. Must be 1–40 characters and contain only letters, digits, underscores, or hyphens.", alias="rcsAgent")
     additional_properties: Dict[str, Any] = {}
-    __properties: ClassVar[List[str]] = ["phoneNumbers"]
+    __properties: ClassVar[List[str]] = ["phoneNumbers", "rcsAgent"]
+
+    @field_validator('rcs_agent')
+    def rcs_agent_validate_regular_expression(cls, value):
+        """Validates the regular expression"""
+        if value is None:
+            return value
+
+        if not re.match(r"^[A-Za-z0-9_-]{1,40}$", value):
+            raise ValueError(r"must validate the regular expression /^[A-Za-z0-9_-]{1,40}$/")
+        return value
 
     model_config = ConfigDict(
         populate_by_name=True,
@@ -90,7 +101,8 @@ def from_dict(cls, obj: Optional[Dict[str, Any]]) -> Optional[Self]:
             return cls.model_validate(obj)
 
         _obj = cls.model_validate({
-            "phoneNumbers": obj.get("phoneNumbers")
+            "phoneNumbers": obj.get("phoneNumbers"),
+            "rcsAgent": obj.get("rcsAgent")
         })
         # store additional fields in additional_properties
         for _key in obj.keys():
diff --git a/docs/SyncLookupRequest.md b/docs/SyncLookupRequest.md
index 7b753251..71c32667 100644
--- a/docs/SyncLookupRequest.md
+++ b/docs/SyncLookupRequest.md
@@ -6,6 +6,7 @@
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **phone_numbers** | **List[str]** | Telephone numbers in E.164 format. | 
+**rcs_agent** | **str** | Override the default RCS sender/agent ID used when checking RCS capabilities. When provided, this value is used as the `sender` in the RCS capability-check request instead of the account default. Must be 1–40 characters and contain only letters, digits, underscores, or hyphens. | [optional] 
 
 ## Example
 
diff --git a/test/unit/api/test_phone_number_lookup_api.py b/test/unit/api/test_phone_number_lookup_api.py
index caec4524..799358eb 100644
--- a/test/unit/api/test_phone_number_lookup_api.py
+++ b/test/unit/api/test_phone_number_lookup_api.py
@@ -82,6 +82,7 @@ def test_create_sync_lookup(self) -> None:
         """
         request = SyncLookupRequest(
             phone_numbers = [USER_NUMBER, BW_NUMBER],
+            rcs_agent = 'TestAgent'
         )
 
         response = self.api.create_sync_lookup_with_http_info(BW_ACCOUNT_ID, request)
diff --git a/test/unit/models/test_sync_lookup_request.py b/test/unit/models/test_sync_lookup_request.py
index d73fcb54..b946135e 100644
--- a/test/unit/models/test_sync_lookup_request.py
+++ b/test/unit/models/test_sync_lookup_request.py
@@ -35,7 +35,8 @@ def make_instance(self, include_optional) -> SyncLookupRequest:
             return SyncLookupRequest(
                 phone_numbers = [
                     '+680728880015'
-                    ]
+                    ],
+                rcs_agent = 'TestAgent'
             )
         else:
             return SyncLookupRequest(
@@ -50,6 +51,7 @@ def testSyncLookupRequest(self):
         assert instance is not None
         assert isinstance(instance, SyncLookupRequest)
         assert instance.phone_numbers == ['+680728880015']
+        assert instance.rcs_agent == 'TestAgent'
 
 if __name__ == '__main__':
     unittest.main()