diff --git a/app/javascript/dashboard/helper/voice.js b/app/javascript/dashboard/helper/voice.js
index 0093f810c..16655b0cb 100644
--- a/app/javascript/dashboard/helper/voice.js
+++ b/app/javascript/dashboard/helper/voice.js
@@ -63,6 +63,7 @@ export function handleVoiceCallUpdated(commit, message, currentUserId) {
   commit(types.UPDATE_MESSAGE_CALL_STATUS, {
     conversationId,
     callStatus: status,
+    callSid,
   });
 
   const isNewCall =
diff --git a/app/javascript/dashboard/store/modules/conversations/index.js b/app/javascript/dashboard/store/modules/conversations/index.js
index 509629001..9afa34ee5 100644
--- a/app/javascript/dashboard/store/modules/conversations/index.js
+++ b/app/javascript/dashboard/store/modules/conversations/index.js
@@ -307,19 +307,23 @@ export const mutations = {
     }
   },
 
-  [types.UPDATE_MESSAGE_CALL_STATUS](_state, { conversationId, callStatus }) {
+  [types.UPDATE_MESSAGE_CALL_STATUS](
+    _state,
+    { conversationId, callStatus, callSid }
+  ) {
     const chat = getConversationById(_state)(conversationId);
     if (!chat) return;
 
-    const lastCall = (chat.messages || []).findLast(
-      m => m.content_type === CONTENT_TYPES.VOICE_CALL
+    const message = (chat.messages || []).find(
+      m =>
+        m.content_type === CONTENT_TYPES.VOICE_CALL &&
+        m.content_attributes?.data?.call_sid === callSid
     );
+    if (!message) return;
 
-    if (!lastCall) return;
-
-    lastCall.content_attributes ??= {};
-    lastCall.content_attributes.data = {
-      ...lastCall.content_attributes.data,
+    message.content_attributes ??= {};
+    message.content_attributes.data = {
+      ...message.content_attributes.data,
       status: callStatus,
     };
   },
diff --git a/app/javascript/dashboard/store/modules/conversations/specs/mutations.spec.js b/app/javascript/dashboard/store/modules/conversations/specs/mutations.spec.js
index 6ac66353e..c535b7a72 100644
--- a/app/javascript/dashboard/store/modules/conversations/specs/mutations.spec.js
+++ b/app/javascript/dashboard/store/modules/conversations/specs/mutations.spec.js
@@ -8,11 +8,12 @@ describe('#mutations', () => {
       mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
         conversationId: 1,
         callStatus: 'ringing',
+        callSid: 'CA123',
       });
       expect(state.allConversations).toEqual([]);
     });
 
-    it('does nothing if no voice call message exists', () => {
+    it('does nothing if no matching voice call message exists', () => {
       const state = {
         allConversations: [
           { id: 1, messages: [{ id: 1, content_type: 'text' }] },
@@ -21,6 +22,7 @@ describe('#mutations', () => {
       mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
         conversationId: 1,
         callStatus: 'ringing',
+        callSid: 'CA123',
       });
       expect(state.allConversations[0].messages[0]).toEqual({
         id: 1,
@@ -28,7 +30,7 @@ describe('#mutations', () => {
       });
     });
 
-    it('updates the last voice call message status', () => {
+    it('updates only the voice call message matching the given callSid', () => {
       const state = {
         allConversations: [
           {
@@ -37,12 +39,16 @@ describe('#mutations', () => {
               {
                 id: 1,
                 content_type: 'voice_call',
-                content_attributes: { data: { status: 'ringing' } },
+                content_attributes: {
+                  data: { call_sid: 'CA111', status: 'ringing' },
+                },
               },
               {
                 id: 2,
                 content_type: 'voice_call',
-                content_attributes: { data: { status: 'ringing' } },
+                content_attributes: {
+                  data: { call_sid: 'CA222', status: 'ringing' },
+                },
               },
             ],
           },
@@ -51,31 +57,14 @@ describe('#mutations', () => {
       mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
         conversationId: 1,
         callStatus: 'in-progress',
+        callSid: 'CA111',
       });
       expect(
         state.allConversations[0].messages[0].content_attributes.data.status
-      ).toBe('ringing');
+      ).toBe('in-progress');
       expect(
         state.allConversations[0].messages[1].content_attributes.data.status
-      ).toBe('in-progress');
-    });
-
-    it('creates content_attributes.data if it does not exist', () => {
-      const state = {
-        allConversations: [
-          {
-            id: 1,
-            messages: [{ id: 1, content_type: 'voice_call' }],
-          },
-        ],
-      };
-      mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
-        conversationId: 1,
-        callStatus: 'completed',
-      });
-      expect(
-        state.allConversations[0].messages[0].content_attributes.data.status
-      ).toBe('completed');
+      ).toBe('ringing');
     });
 
     it('preserves existing data in content_attributes.data', () => {
@@ -98,6 +87,7 @@ describe('#mutations', () => {
       mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
         conversationId: 1,
         callStatus: 'in-progress',
+        callSid: 'CA123',
       });
       expect(
         state.allConversations[0].messages[0].content_attributes.data
@@ -114,6 +104,7 @@ describe('#mutations', () => {
       mutations[types.UPDATE_MESSAGE_CALL_STATUS](state, {
         conversationId: 1,
         callStatus: 'ringing',
+        callSid: 'CA123',
       });
       expect(state.allConversations[0].messages).toEqual([]);
     });
diff --git a/enterprise/app/controllers/api/v1/accounts/conference_controller.rb b/enterprise/app/controllers/api/v1/accounts/conference_controller.rb
index 6756ea33f..3361beac2 100644
--- a/enterprise/app/controllers/api/v1/accounts/conference_controller.rb
+++ b/enterprise/app/controllers/api/v1/accounts/conference_controller.rb
@@ -33,14 +33,10 @@ class Api::V1::Accounts::ConferenceController < Api::V1::Accounts::BaseControlle
   private
 
   def resolve_call!
-    inbox_calls = Call.where(inbox_id: @voice_inbox.id, provider: :twilio)
+    sid = params[:call_sid].presence
+    raise ActionController::ParameterMissing, :call_sid if sid.blank?
 
-    if params[:call_sid].present?
-      inbox_calls.find_by!(provider_call_id: params[:call_sid])
-    else
-      conversation = fetch_conversation_by_display_id
-      inbox_calls.where(conversation_id: conversation.id).active.order(created_at: :desc).first!
-    end
+    Call.where(inbox_id: @voice_inbox.id, provider: :twilio).find_by!(provider_call_id: sid)
   end
 
   def set_voice_inbox_for_conference
diff --git a/enterprise/app/controllers/twilio/voice_controller.rb b/enterprise/app/controllers/twilio/voice_controller.rb
index 0f1892d38..72ea49a51 100644
--- a/enterprise/app/controllers/twilio/voice_controller.rb
+++ b/enterprise/app/controllers/twilio/voice_controller.rb
@@ -95,14 +95,10 @@ class Twilio::VoiceController < ApplicationController
   end
 
   def find_call_for_agent
-    if params[:call_sid].present?
-      Call.find_by!(provider: :twilio, provider_call_id: params[:call_sid])
-    elsif params[:conversation_id].present?
-      conversation = current_account.conversations.find_by!(display_id: params[:conversation_id])
-      Call.where(conversation_id: conversation.id).active.order(created_at: :desc).first!
-    else
-      Call.find_by!(provider: :twilio, provider_call_id: twilio_call_sid)
-    end
+    sid = params[:call_sid].presence
+    raise ArgumentError, 'call_sid is required for agent leg' if sid.blank?
+
+    Call.find_by!(provider: :twilio, provider_call_id: sid)
   end
 
   def sync_outbound_leg(call_sid:, direction:)
@@ -141,9 +137,10 @@ class Twilio::VoiceController < ApplicationController
   end
 
   def find_call_for_conference!(friendly_name:, call_sid:)
+    inbox_calls = Call.where(inbox_id: inbox.id, provider: :twilio)
     name = friendly_name.to_s
-    call = Call.twilio.by_conference_sid(name).first if name.present?
-    call || Call.find_by!(provider: :twilio, provider_call_id: call_sid)
+    call = inbox_calls.by_conference_sid(name).first if name.present?
+    call || inbox_calls.find_by!(provider_call_id: call_sid)
   end
 
   def set_inbox!
diff --git a/enterprise/app/services/voice/conference/manager.rb b/enterprise/app/services/voice/conference/manager.rb
index d86b70457..c6115137b 100644
--- a/enterprise/app/services/voice/conference/manager.rb
+++ b/enterprise/app/services/voice/conference/manager.rb
@@ -23,6 +23,9 @@ class Voice::Conference::Manager
   end
 
   def mark_ringing!
+    # Guard against delayed conference-start retries rolling a progressed call back to ringing.
+    return unless call.status == 'ringing'
+
     status_manager.process_status_update('ringing')
   end
 
diff --git a/enterprise/app/services/voice/status_update_service.rb b/enterprise/app/services/voice/status_update_service.rb
index 7ff22f2c9..db854b2c3 100644
--- a/enterprise/app/services/voice/status_update_service.rb
+++ b/enterprise/app/services/voice/status_update_service.rb
@@ -19,7 +19,7 @@ class Voice::StatusUpdateService
     normalized_status = normalize_status(call_status)
     return if normalized_status.blank?
 
-    call = Call.find_by_provider_call_id(:twilio, call_sid)
+    call = Call.where(account_id: account.id).find_by(provider: :twilio, provider_call_id: call_sid)
     return unless call
 
     Voice::CallStatus::Manager.new(call: call).process_status_update(
diff --git a/spec/enterprise/controllers/api/v1/accounts/conference_controller_spec.rb b/spec/enterprise/controllers/api/v1/accounts/conference_controller_spec.rb
index ffb397464..c35689c84 100644
--- a/spec/enterprise/controllers/api/v1/accounts/conference_controller_spec.rb
+++ b/spec/enterprise/controllers/api/v1/accounts/conference_controller_spec.rb
@@ -91,13 +91,13 @@ RSpec.describe Api::V1::Accounts::ConferenceController, type: :request do
         expect(conference_service).to have_received(:mark_agent_joined)
       end
 
-      it 'falls back to the most recent active call on the conversation when call_sid is missing' do
+      it 'rejects the request when call_sid is missing' do
         post "/api/v1/accounts/#{account.id}/inboxes/#{voice_inbox.id}/conference",
              headers: agent.create_new_auth_token,
              params: { conversation_id: conversation.display_id }
 
-        expect(response).to have_http_status(:ok)
-        expect(conference_service).to have_received(:ensure_conference_sid)
+        expect(response).to have_http_status(:unprocessable_content)
+        expect(conference_service).not_to have_received(:ensure_conference_sid)
       end
 
       it 'does not allow accessing calls from inboxes without access' do