diff --git a/Signal/src/Signal-Bridging-Header.h b/Signal/src/Signal-Bridging-Header.h
index e4323e894..a34c03dc7 100644
--- a/Signal/src/Signal-Bridging-Header.h
+++ b/Signal/src/Signal-Bridging-Header.h
@@ -87,7 +87,6 @@
 #import <SignalServiceKit/OWSCallHangupMessage.h>
 #import <SignalServiceKit/OWSCallIceUpdateMessage.h>
 #import <SignalServiceKit/OWSCallMessageHandler.h>
-#import <SignalServiceKit/OWSCallOfferMessage.h>
 #import <SignalServiceKit/OWSContactsOutputStream.h>
 #import <SignalServiceKit/OWSDispatch.h>
 #import <SignalServiceKit/OWSEndSessionMessage.h>
diff --git a/Signal/src/call/CallService.swift b/Signal/src/call/CallService.swift
index cadbcc4d7..e5e2ca138 100644
--- a/Signal/src/call/CallService.swift
+++ b/Signal/src/call/CallService.swift
@@ -78,6 +78,7 @@ public enum CallError: Error {
     case externalError(underlyingError: Error)
     case timeout(description: String)
     case obsoleteCall(description: String)
+    case protoErro(description: String)
 }
 
 // Should be roughly synced with Android client for consistency
@@ -407,9 +408,17 @@ private class SignalCallData: NSObject {
             }
 
             return peerConnectionClient.setLocalSessionDescription(sessionDescription).then {
-                let offerMessage = OWSCallOfferMessage(callId: call.signalingId, sessionDescription: sessionDescription.sdp)
-                let callMessage = OWSOutgoingCallMessage(thread: call.thread, offerMessage: offerMessage)
-                return self.messageSender.sendPromise(message: callMessage)
+                let offerBuilder = SSKProtoCallMessageOffer.SSKProtoCallMessageOfferBuilder()
+                offerBuilder.setId(call.signalingId)
+                offerBuilder.setSessionDescription(sessionDescription.sdp)
+                do {
+                    let offer = try offerBuilder.build()
+                    let callMessage = OWSOutgoingCallMessage(thread: call.thread, offerMessage: offer)
+                    return self.messageSender.sendPromise(message: callMessage)
+                } catch {
+                    owsFail("Couldn't build proto in \(#function)")
+                    throw CallError.protoErro(description: "Couldn't build proto in \(#function)")
+                }
             }
         }.then {
             guard self.call == call else {
diff --git a/SignalServiceKit/src/Messages/OWSCallOfferMessage.h b/SignalServiceKit/src/Messages/OWSCallOfferMessage.h
deleted file mode 100644
index 3006991ef..000000000
--- a/SignalServiceKit/src/Messages/OWSCallOfferMessage.h
+++ /dev/null
@@ -1,23 +0,0 @@
-//
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
-//
-
-NS_ASSUME_NONNULL_BEGIN
-
-@class SSKProtoCallMessageOffer;
-
-/**
- * Sent by the call initiator to Signal their intention to set up a call with the recipient.
- */
-@interface OWSCallOfferMessage : NSObject
-
-- (instancetype)initWithCallId:(UInt64)callId sessionDescription:(NSString *)sessionDescription;
-
-@property (nonatomic, readonly) UInt64 callId;
-@property (nonatomic, readonly, copy) NSString *sessionDescription;
-
-- (nullable SSKProtoCallMessageOffer *)asProtobuf;
-
-@end
-
-NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Messages/OWSCallOfferMessage.m b/SignalServiceKit/src/Messages/OWSCallOfferMessage.m
deleted file mode 100644
index 27e631289..000000000
--- a/SignalServiceKit/src/Messages/OWSCallOfferMessage.m
+++ /dev/null
@@ -1,43 +0,0 @@
-//
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
-//
-
-#import "OWSCallOfferMessage.h"
-#import <SignalServiceKit/SignalServiceKit-Swift.h>
-
-NS_ASSUME_NONNULL_BEGIN
-
-@implementation OWSCallOfferMessage
-
-- (instancetype)initWithCallId:(UInt64)callId sessionDescription:(NSString *)sessionDescription
-{
-    self = [super init];
-    if (!self) {
-        return self;
-    }
-
-    _callId = callId;
-    _sessionDescription = sessionDescription;
-
-    return self;
-}
-
-- (nullable SSKProtoCallMessageOffer *)asProtobuf
-{
-    SSKProtoCallMessageOfferBuilder *builder = [SSKProtoCallMessageOfferBuilder new];
-
-    builder.id = self.callId;
-    builder.sessionDescription = self.sessionDescription;
-    
-    NSError *error;
-    SSKProtoCallMessageOffer *_Nullable result = [builder buildAndReturnError:&error];
-    if (error || !result) {
-        OWSFail(@"%@ could not build protobuf: %@", self.logTag, error);
-        return nil;
-    }
-    return result;
-}
-
-@end
-
-NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.h b/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.h
index 314460b4e..c9580d4ad 100644
--- a/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.h
+++ b/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.h
@@ -10,7 +10,7 @@ NS_ASSUME_NONNULL_BEGIN
 @class OWSCallBusyMessage;
 @class OWSCallHangupMessage;
 @class OWSCallIceUpdateMessage;
-@class OWSCallOfferMessage;
+@class SSKProtoCallMessageOffer;
 @class TSThread;
 
 /**
@@ -29,7 +29,7 @@ NS_ASSUME_NONNULL_BEGIN
                                    quotedMessage:(nullable TSQuotedMessage *)quotedMessage
                                     contactShare:(nullable OWSContact *)contactShare NS_UNAVAILABLE;
 
-- (instancetype)initWithThread:(TSThread *)thread offerMessage:(OWSCallOfferMessage *)offerMessage;
+- (instancetype)initWithThread:(TSThread *)thread offerMessage:(SSKProtoCallMessageOffer *)offerMessage;
 - (instancetype)initWithThread:(TSThread *)thread answerMessage:(OWSCallAnswerMessage *)answerMessage;
 - (instancetype)initWithThread:(TSThread *)thread iceUpdateMessage:(OWSCallIceUpdateMessage *)iceUpdateMessage;
 - (instancetype)initWithThread:(TSThread *)thread
@@ -37,11 +37,11 @@ NS_ASSUME_NONNULL_BEGIN
 - (instancetype)initWithThread:(TSThread *)thread hangupMessage:(OWSCallHangupMessage *)hangupMessage;
 - (instancetype)initWithThread:(TSThread *)thread busyMessage:(OWSCallBusyMessage *)busyMessage;
 
-@property (nullable, nonatomic, readonly, strong) OWSCallOfferMessage *offerMessage;
-@property (nullable, nonatomic, readonly, strong) OWSCallAnswerMessage *answerMessage;
-@property (nullable, nonatomic, readonly, strong) NSArray<OWSCallIceUpdateMessage *> *iceUpdateMessages;
-@property (nullable, nonatomic, readonly, strong) OWSCallHangupMessage *hangupMessage;
-@property (nullable, nonatomic, readonly, strong) OWSCallBusyMessage *busyMessage;
+@property (nullable, nonatomic, readonly) SSKProtoCallMessageOffer *offerMessage;
+@property (nullable, nonatomic, readonly) OWSCallAnswerMessage *answerMessage;
+@property (nullable, nonatomic, readonly) NSArray<OWSCallIceUpdateMessage *> *iceUpdateMessages;
+@property (nullable, nonatomic, readonly) OWSCallHangupMessage *hangupMessage;
+@property (nullable, nonatomic, readonly) OWSCallBusyMessage *busyMessage;
 
 @end
 
diff --git a/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.m b/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.m
index dfba56952..83f5fe605 100644
--- a/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.m
+++ b/SignalServiceKit/src/Messages/OWSOutgoingCallMessage.m
@@ -8,7 +8,6 @@
 #import "OWSCallBusyMessage.h"
 #import "OWSCallHangupMessage.h"
 #import "OWSCallIceUpdateMessage.h"
-#import "OWSCallOfferMessage.h"
 #import "ProtoUtils.h"
 #import "SignalRecipient.h"
 #import "TSContactThread.h"
@@ -39,7 +38,7 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
-- (instancetype)initWithThread:(TSThread *)thread offerMessage:(OWSCallOfferMessage *)offerMessage
+- (instancetype)initWithThread:(TSThread *)thread offerMessage:(SSKProtoCallMessageOffer *)offerMessage
 {
     self = [self initWithThread:thread];
     if (!self) {
@@ -147,11 +146,7 @@ NS_ASSUME_NONNULL_BEGIN
     SSKProtoCallMessageBuilder *builder = [SSKProtoCallMessageBuilder new];
 
     if (self.offerMessage) {
-        SSKProtoCallMessageOffer *_Nullable proto = [self.offerMessage asProtobuf];
-        if (!proto) {
-            return nil;
-        }
-        [builder setOffer:proto];
+        [builder setOffer:self.offerMessage];
     }
 
     if (self.answerMessage) {