diff --git a/app/clients/cbc_proxy.py b/app/clients/cbc_proxy.py
index a52eac80d..8500e57c4 100644
--- a/app/clients/cbc_proxy.py
+++ b/app/clients/cbc_proxy.py
@@ -1,7 +1,9 @@
 import json
+from abc import ABC, abstractmethod
 
 import boto3
 from flask import current_app
+from notifications_utils.template import non_gsm_characters
 
 from app.config import BroadcastProvider
 from app.utils import DATETIME_FORMAT, format_sequential_number
@@ -48,9 +50,19 @@ class CBCProxyClient:
         return proxy_classes[provider](self._lambda_client)
 
 
-class CBCProxyClientBase:
+class CBCProxyClientBase(ABC):
     lambda_name = None
 
+    @property
+    @abstractmethod
+    def LANGUAGE_ENGLISH(self):
+        pass
+
+    @property
+    @abstractmethod
+    def LANGUAGE_WELSH(self):
+        pass
+
     def __init__(self, lambda_client):
         self._lambda_client = lambda_client
 
@@ -111,6 +123,11 @@ class CBCProxyClientBase:
 
         return result
 
+    def infer_language_from(self, content):
+        if non_gsm_characters(content):
+            return self.LANGUAGE_WELSH
+        return self.LANGUAGE_ENGLISH
+
 
 class CBCProxyCanary(CBCProxyClientBase):
     """
@@ -119,6 +136,9 @@ class CBCProxyCanary(CBCProxyClientBase):
     """
     lambda_name = 'canary'
 
+    LANGUAGE_ENGLISH = None
+    LANGUAGE_WELSH = None
+
     def send_canary(
         self,
         identifier,
@@ -129,6 +149,9 @@ class CBCProxyCanary(CBCProxyClientBase):
 class CBCProxyEE(CBCProxyClientBase):
     lambda_name = 'bt-ee-1-proxy'
 
+    LANGUAGE_ENGLISH = 'en-GB'
+    LANGUAGE_WELSH = 'cy-GB'
+
     def send_link_test(
         self,
         identifier,
@@ -158,6 +181,7 @@ class CBCProxyEE(CBCProxyClientBase):
             'areas': areas,
             'sent': sent,
             'expires': expires,
+            'language': self.infer_language_from(description),
         }
         self._invoke_lambda(payload=payload)
 
@@ -184,6 +208,9 @@ class CBCProxyEE(CBCProxyClientBase):
 class CBCProxyVodafone(CBCProxyClientBase):
     lambda_name = 'vodafone-1-proxy'
 
+    LANGUAGE_ENGLISH = 'English'
+    LANGUAGE_WELSH = 'Welsh'
+
     def send_link_test(
         self,
         identifier,
@@ -215,6 +242,7 @@ class CBCProxyVodafone(CBCProxyClientBase):
             'areas': areas,
             'sent': sent,
             'expires': expires,
+            'language': self.infer_language_from(description),
         }
         self._invoke_lambda(payload=payload)
 
diff --git a/tests/app/clients/test_cbc_proxy.py b/tests/app/clients/test_cbc_proxy.py
index 742e97736..c8db4cc45 100644
--- a/tests/app/clients/test_cbc_proxy.py
+++ b/tests/app/clients/test_cbc_proxy.py
@@ -59,10 +59,18 @@ def test_cbc_proxy_lambda_client_has_correct_keys(cbc_proxy_ee):
     assert secret == 'cbc-proxy-aws-secret-access-key'
 
 
-def test_cbc_proxy_ee_create_and_send_invokes_function(mocker, cbc_proxy_ee):
+@pytest.mark.parametrize('description, expected_language', (
+    ('my-description', 'en-GB'),
+    ('mŷ-description', 'cy-GB'),
+))
+def test_cbc_proxy_ee_create_and_send_invokes_function(
+    mocker,
+    cbc_proxy_ee,
+    description,
+    expected_language,
+):
     identifier = 'my-identifier'
     headline = 'my-headline'
-    description = 'my-description'
 
     sent = 'a-passed-through-sent-value'
     expires = 'a-passed-through-expires-value'
@@ -117,6 +125,7 @@ def test_cbc_proxy_ee_create_and_send_invokes_function(mocker, cbc_proxy_ee):
     assert payload['areas'] == areas
     assert payload['sent'] == sent
     assert payload['expires'] == expires
+    assert payload['language'] == expected_language
 
 
 def test_cbc_proxy_ee_cancel_invokes_function(mocker, cbc_proxy_ee):
@@ -175,10 +184,18 @@ def test_cbc_proxy_ee_cancel_invokes_function(mocker, cbc_proxy_ee):
     assert payload['sent'] == sent
 
 
-def test_cbc_proxy_vodafone_create_and_send_invokes_function(mocker, cbc_proxy_vodafone):
+@pytest.mark.parametrize('description, expected_language', (
+    ('my-description', 'English'),
+    ('mŷ-description', 'Welsh'),
+))
+def test_cbc_proxy_vodafone_create_and_send_invokes_function(
+    mocker,
+    cbc_proxy_vodafone,
+    description,
+    expected_language,
+):
     identifier = 'my-identifier'
     headline = 'my-headline'
-    description = 'my-description'
 
     sent = 'a-passed-through-sent-value'
     expires = 'a-passed-through-expires-value'
@@ -233,6 +250,7 @@ def test_cbc_proxy_vodafone_create_and_send_invokes_function(mocker, cbc_proxy_v
     assert payload['areas'] == areas
     assert payload['sent'] == sent
     assert payload['expires'] == expires
+    assert payload['language'] == expected_language
 
 
 def test_cbc_proxy_vodafone_cancel_invokes_function(mocker, cbc_proxy_vodafone):