diff --git a/app/controllers/users/two_factor_authentication_controller.rb b/app/controllers/users/two_factor_authentication_controller.rb
index b380d7767e3..b3d4eeec0ed 100644
--- a/app/controllers/users/two_factor_authentication_controller.rb
+++ b/app/controllers/users/two_factor_authentication_controller.rb
@@ -224,19 +224,22 @@ def track_events(otp_delivery_preference:)
       if UserSessionContext.reauthentication_context?(context)
         irs_attempts_api_tracker.mfa_login_phone_otp_sent(
           reauthentication: true,
-          phone_number: parsed_phone.e164,
           success: @telephony_result.success?,
+          phone_number: parsed_phone.e164,
+          otp_delivery_method: otp_delivery_preference,
         )
       elsif UserSessionContext.authentication_context?(context)
         irs_attempts_api_tracker.mfa_login_phone_otp_sent(
           reauthentication: false,
-          phone_number: parsed_phone.e164,
           success: @telephony_result.success?,
+          phone_number: parsed_phone.e164,
+          otp_delivery_method: otp_delivery_preference,
         )
       elsif UserSessionContext.confirmation_context?(context)
         irs_attempts_api_tracker.mfa_enroll_phone_otp_sent(
-          phone_number: parsed_phone.e164,
           success: @telephony_result.success?,
+          phone_number: parsed_phone.e164,
+          otp_delivery_method: otp_delivery_preference,
         )
       end
     end
diff --git a/app/services/irs_attempts_api/tracker_events.rb b/app/services/irs_attempts_api/tracker_events.rb
index a7cedd5b361..33f4746308d 100644
--- a/app/services/irs_attempts_api/tracker_events.rb
+++ b/app/services/irs_attempts_api/tracker_events.rb
@@ -195,7 +195,7 @@ def idv_personal_key_generated(success:)
 
     # @param [Boolean] success
     # @param [String] phone_number
-    # @param [String] otp_delivery_method
+    # @param [String] otp_delivery_method - Either SMS or Voice
     # @param [Hash<Key, Array<String>>] failure_reason
     # Track when OTP is sent and what method chosen during idv flow.
     def idv_phone_confirmation_otp_sent(success:, phone_number:,
@@ -426,15 +426,17 @@ def mfa_enroll_options_selected(success:, mfa_device_types:)
       )
     end
 
-    # @param [String] phone_number - The user's phone_number used for multi-factor authentication
     # @param [Boolean] success - True if the OTP Verification was sent
+    # @param [String] phone_number - The user's phone_number used for multi-factor authentication
+    # @param [String] otp_delivery_method - Either SMS or Voice
     # Relevant only when the user is enrolling a phone as their MFA.
-    # The user has been sent an OTP by login.gov over SMS during the MFA enrollment process.
-    def mfa_enroll_phone_otp_sent(phone_number:, success:)
+    # The user has been sent an OTP and by SMS or Voice during the MFA enrollment process.
+    def mfa_enroll_phone_otp_sent(success:, phone_number:, otp_delivery_method:)
       track_event(
         :mfa_enroll_phone_otp_sent,
-        phone_number: phone_number,
         success: success,
+        phone_number: phone_number,
+        otp_delivery_method: otp_delivery_method,
       )
     end
 
@@ -521,15 +523,17 @@ def mfa_login_backup_code(success:)
     end
 
     # @param [Boolean] reauthentication - True if the user was already logged in
-    # @param [String] phone_number - The user's phone_number used for multi-factor authentication
     # @param [Boolean] success - True if the OTP Verification was sent
-    # During a login attempt, an OTP code has been sent via SMS.
-    def mfa_login_phone_otp_sent(reauthentication:, phone_number:, success:)
+    # @param [String] phone_number - The user's phone_number used for multi-factor authentication
+    # @param [String] otp_delivery_method - Either SMS or Voice
+    # During a login attempt, an OTP code has been sent via SMS or Voice.
+    def mfa_login_phone_otp_sent(reauthentication:, success:, phone_number:, otp_delivery_method:)
       track_event(
         :mfa_login_phone_otp_sent,
         reauthentication: reauthentication,
-        phone_number: phone_number,
         success: success,
+        phone_number: phone_number,
+        otp_delivery_method: otp_delivery_method,
       )
     end
 
diff --git a/spec/controllers/users/two_factor_authentication_controller_spec.rb b/spec/controllers/users/two_factor_authentication_controller_spec.rb
index ab63bfd2320..534f711f3e0 100644
--- a/spec/controllers/users/two_factor_authentication_controller_spec.rb
+++ b/spec/controllers/users/two_factor_authentication_controller_spec.rb
@@ -327,7 +327,12 @@ def index
       it 'tracks the verification attempt event' do
         stub_attempts_tracker
         expect(@irs_attempts_api_tracker).to receive(:mfa_login_phone_otp_sent).
-          with(phone_number: '+12025551212', reauthentication: false, success: true)
+          with(
+            phone_number: '+12025551212',
+            reauthentication: false,
+            success: true,
+            otp_delivery_method: 'sms',
+          )
 
         get :send_code, params: { otp_delivery_selection_form:
           { otp_delivery_preference: 'sms' } }
@@ -338,7 +343,12 @@ def index
         subject.user_session[:context] = 'reauthentication'
 
         expect(@irs_attempts_api_tracker).to receive(:mfa_login_phone_otp_sent).
-          with(phone_number: '+12025551212', reauthentication: true, success: true)
+          with(
+            phone_number: '+12025551212',
+            reauthentication: true,
+            success: true,
+            otp_delivery_method: 'sms',
+          )
 
         get :send_code, params: { otp_delivery_selection_form:
           { otp_delivery_preference: 'sms' } }
@@ -532,7 +542,7 @@ def index
 
         stub_attempts_tracker
         expect(@irs_attempts_api_tracker).to receive(:mfa_enroll_phone_otp_sent).
-          with({ phone_number: '+12025551213', success: true })
+          with({ phone_number: '+12025551213', success: true, otp_delivery_method: 'sms' })
 
         get :send_code, params: { otp_delivery_selection_form: { otp_delivery_preference: 'sms' } }
       end