diff --git a/sipsimple/__info__.py b/sipsimple/__info__.py
index 57091425..3d010e8f 100644
--- a/sipsimple/__info__.py
+++ b/sipsimple/__info__.py
@@ -1,14 +1,14 @@
 
 """Package information"""
 
 __project__ = "python3-sipsimple"
 __summary__ = "SIP SIMPLE implementation for Python"
 __webpage__ = "https://sipsimpleclient.org"
 
-__version__ = "4.0.0"
+__version__ = "4.0.1"
 
 __author__ = "AG Projects"
 __email__ = "support@ag-projects.com"
 
 __license__ = "GPL"
 __copyright__ = "Copyright 2008-2021 {}".format(__author__)
diff --git a/sipsimple/core/__init__.py b/sipsimple/core/__init__.py
index ffaa09b2..da76ae7b 100644
--- a/sipsimple/core/__init__.py
+++ b/sipsimple/core/__init__.py
@@ -1,12 +1,12 @@
 
 from sipsimple.core._core import *
 from sipsimple.core._engine import *
 from sipsimple.core._helpers import *
 from sipsimple.core._primitives import *
 
-required_revision = 182
+required_revision = 183
 if CORE_REVISION != required_revision:
     raise ImportError("Wrong SIP core revision %d (expected %d)" % (CORE_REVISION, required_revision))
 del required_revision
 
 
diff --git a/sipsimple/core/_core.pyx b/sipsimple/core/_core.pyx
index 592b700e..588540b3 100644
--- a/sipsimple/core/_core.pyx
+++ b/sipsimple/core/_core.pyx
@@ -1,54 +1,54 @@
 
 include "_core.error.pxi"
 include "_core.lib.pxi"
 include "_core.sound.pxi"
 include "_core.video.pxi"
 include "_core.util.pxi"
 
 include "_core.ua.pxi"
 
 include "_core.event.pxi"
 include "_core.request.pxi"
 include "_core.helper.pxi"
 include "_core.headers.pxi"
 include "_core.subscription.pxi"
 include "_core.invitation.pxi"
 include "_core.referral.pxi"
 include "_core.sdp.pxi"
 include "_core.mediatransport.pxi"
 
 # constants
 
 PJ_VERSION = pj_get_version()
 PJ_SVN_REVISION = int(PJ_SVN_REV)
-CORE_REVISION = 182
+CORE_REVISION = 183
 
 # exports
 
 __all__ = ["PJ_VERSION", "PJ_SVN_REVISION", "CORE_REVISION",
            "SIPCoreError", "PJSIPError", "PJSIPTLSError", "SIPCoreInvalidStateError",
            "AudioMixer", "ToneGenerator", "RecordingWaveFile", "WaveFile", "MixerPort",
            "VideoCamera", "FrameBufferVideoRenderer",
            "sip_status_messages",
            "BaseCredentials", "Credentials", "FrozenCredentials", "BaseSIPURI", "SIPURI", "FrozenSIPURI",
            "BaseHeader", "Header", "FrozenHeader",
            "BaseContactHeader", "ContactHeader", "FrozenContactHeader",
            "BaseContentTypeHeader", "ContentType", "ContentTypeHeader", "FrozenContentTypeHeader",
            "BaseIdentityHeader", "IdentityHeader", "FrozenIdentityHeader", "FromHeader", "FrozenFromHeader", "ToHeader", "FrozenToHeader",
            "RouteHeader", "FrozenRouteHeader", "RecordRouteHeader", "FrozenRecordRouteHeader", "BaseRetryAfterHeader", "RetryAfterHeader", "FrozenRetryAfterHeader",
            "BaseViaHeader", "ViaHeader", "FrozenViaHeader", "BaseWarningHeader", "WarningHeader", "FrozenWarningHeader",
            "BaseEventHeader", "EventHeader", "FrozenEventHeader", "BaseSubscriptionStateHeader", "SubscriptionStateHeader", "FrozenSubscriptionStateHeader",
            "BaseReasonHeader", "ReasonHeader", "FrozenReasonHeader",
            "BaseReferToHeader", "ReferToHeader", "FrozenReferToHeader",
            "BaseSubjectHeader", "SubjectHeader", "FrozenSubjectHeader",
            "BaseReplacesHeader", "ReplacesHeader", "FrozenReplacesHeader",
            "Request",
            "Referral",
            "sipfrag_re",
            "Subscription",
            "Invitation",
            "DialogID",
            "SDPSession", "FrozenSDPSession", "SDPMediaStream", "FrozenSDPMediaStream", "SDPConnection", "FrozenSDPConnection", "SDPAttribute", "FrozenSDPAttribute", "SDPNegotiator",
            "RTPTransport", "AudioTransport", "VideoTransport"]