diff --git a/src/ca/cacNotifyIO.cpp b/src/ca/cacNotifyIO.cpp
index 3935ad74c..ac3a93122 100644
--- a/src/ca/cacNotifyIO.cpp
+++ b/src/ca/cacNotifyIO.cpp
@@ -26,7 +26,3 @@ cacNotifyIO::~cacNotifyIO ()
     }
 }
 
-void cacNotifyIO::destroy ()
-{
-    delete this;
-}
diff --git a/src/ca/iocinf.h b/src/ca/iocinf.h
index 3518934ba..5867c0e7a 100644
--- a/src/ca/iocinf.h
+++ b/src/ca/iocinf.h
@@ -298,7 +298,6 @@ public:
     bool identifierEquivelence ( unsigned idToMatch );
     void * operator new ( size_t size );
     void operator delete ( void *pCadaver, size_t size );
-    void unistallSubscription ( class netSubscription & );
     void resetRetryCount ();
     unsigned getRetrySeqNo () const;
     void accessRightsStateChange ( const caar &arIn );
@@ -348,8 +347,9 @@ public:
     virtual void exceptionNotify ( int status, const char *pContext, unsigned type, unsigned long count ) = 0;
     virtual class netSubscription * isSubscription ();
     virtual void show ( unsigned level ) const;
+    virtual void uninstall () = 0;
     ca_uint32_t getID () const;
-    nciu & channel ();
+    nciu & channel () const;
     void destroy ();
 protected:
     nciu &chan;
@@ -362,15 +362,15 @@ public:
     void show ( unsigned level ) const;
     void * operator new ( size_t size );
     void operator delete ( void *pCadaver, size_t size );
-    void destroy ();
-    unsigned long getCount ();
-    unsigned getType ();
-    unsigned getMask ();
+    unsigned long getCount () const;
+    unsigned getType () const;
+    unsigned getMask () const;
 private:
     unsigned long count;
     unsigned type;
     unsigned mask;
 
+    void uninstall ();
     void completionNotify ();
     void completionNotify ( unsigned type, unsigned long count, const void *pData );
     void exceptionNotify ( int status, const char *pContext );
@@ -392,11 +392,11 @@ private:
     unsigned long count;
     void *pValue;
     unsigned seqNumber;
-    void destroy ();
     void completionNotify ();
     void completionNotify ( unsigned type, unsigned long count, const void *pData );
     void exceptionNotify ( int status, const char *pContext );
     void exceptionNotify ( int status, const char *pContext, unsigned type, unsigned long count );
+    void uninstall ();
     ~netReadCopyIO (); // must be allocated from pool
     static tsFreeList < class netReadCopyIO, 1024 > freeList;
 };
@@ -408,7 +408,7 @@ public:
     void * operator new ( size_t size );
     void operator delete ( void *pCadaver, size_t size );
 private:
-    void destroy ();
+    void uninstall ();
     void completionNotify ();
     void completionNotify ( unsigned type, unsigned long count, const void *pData );
     void exceptionNotify ( int status, const char *pContext );
@@ -424,7 +424,7 @@ public:
     void * operator new ( size_t size );
     void operator delete ( void *pCadaver, size_t size );
 private:
-    void destroy ();
+    void uninstall ();
     void completionNotify ();
     void completionNotify ( unsigned type, unsigned long count, const void *pData );
     void exceptionNotify ( int status, const char *pContext );
@@ -488,19 +488,18 @@ public:
     void show ( unsigned level ) const;
     unsigned channelCount () const;
     void disconnectAllChan ( netiiu & newiiu );
+    void destroyAllIO ( nciu &chan );
     void connectTimeoutNotify ();
     bool searchMsg ( unsigned short retrySeqNumber, unsigned &retryNoForThisChannel );
     void resetChannelRetryCounts ();
     void attachChannel ( nciu &chan );
     void detachChannel ( nciu &chan );
     int installSubscription ( netSubscription &subscr );
-    void unistallSubscription ( netSubscription &subscr );
     virtual void hostName (char *pBuf, unsigned bufLength) const;
     virtual const char * pHostName () const; // deprecated - please do not use
     virtual bool isVirtaulCircuit ( const char *pChannelName, const osiSockAddr &addr ) const;
     virtual bool ca_v42_ok () const;
     virtual bool ca_v41_ok () const;
-
     virtual bool pushDatagramMsg ( const caHdr &hdr, const void *pExt, ca_uint16_t extsize);
     virtual int writeRequest ( nciu &, unsigned type, unsigned nElem, const void *pValue);
     virtual int writeNotifyRequest ( nciu &, cacNotify &, unsigned type, unsigned nElem, const void *pValue );
@@ -510,6 +509,8 @@ public:
     virtual void connectAllIO ( nciu &chan );
     virtual void disconnectAllIO ( nciu &chan );
     virtual int clearChannelRequest ( nciu & );
+    virtual void uninstallIO ( baseNMIU & );
+    virtual void subscriptionCancelRequest ( netSubscription &subscr, bool userThread  );
 
 protected:
     cac * pCAC () const;
@@ -521,7 +522,6 @@ private:
 
     virtual void lastChannelDetachNotify ();
     virtual int subscriptionRequest ( netSubscription &subscr, bool userThread );
-    virtual int subscriptionCancelRequest ( netSubscription &subscr, bool userThread  );
 };
 
 class limboiiu : public netiiu {
@@ -831,9 +831,10 @@ private:
        int status, const char *pContext, unsigned type, unsigned long count );
     void connectAllIO ( nciu &chan );
     void disconnectAllIO ( nciu &chan );
+    void uninstallIO ( baseNMIU & );
 
     int subscriptionRequest ( netSubscription &subscr, bool userThread );
-    int subscriptionCancelRequest ( netSubscription &subscr, bool userThread  );
+    void subscriptionCancelRequest ( netSubscription &subscr, bool userThread );
 
     typedef void ( tcpiiu::*pProtoStubTCP ) ();
     static const pProtoStubTCP tcpJumpTableCAC [];
diff --git a/src/ca/nciu.cpp b/src/ca/nciu.cpp
index a74c76446..aa9508703 100644
--- a/src/ca/nciu.cpp
+++ b/src/ca/nciu.cpp
@@ -67,7 +67,7 @@ void nciu::destroy ()
 {
     // this occurs here so that it happens when
     // a lock is not applied
-    this->piiu->disconnectAllIO ( *this );
+    this->piiu->destroyAllIO ( *this );
     this->piiu->clearChannelRequest ( *this );
     this->cacCtx.destroyNCIU ( *this );
 }
diff --git a/src/ca/nciu_IL.h b/src/ca/nciu_IL.h
index dd48fed93..f2cfba546 100644
--- a/src/ca/nciu_IL.h
+++ b/src/ca/nciu_IL.h
@@ -127,9 +127,3 @@ inline netiiu * nciu::getPIIU ()
     return this->piiu;
 }
 
-inline void nciu::unistallSubscription ( netSubscription &subscr )
-{
-    this->piiu->unistallSubscription ( subscr );
-}
-
-
diff --git a/src/ca/netReadCopyIO.cpp b/src/ca/netReadCopyIO.cpp
index f657234a9..45c5f0f94 100644
--- a/src/ca/netReadCopyIO.cpp
+++ b/src/ca/netReadCopyIO.cpp
@@ -29,6 +29,11 @@ netReadCopyIO::~netReadCopyIO ()
 
 }
 
+void netReadCopyIO::uninstall ()
+{
+    this->chan.getPIIU ()->uninstallIO ( *this );
+}
+
 void netReadCopyIO::completionNotify ()
 {
     this->exceptionNotify ( ECA_INTERNAL, "get completion callback with no data?" );
diff --git a/src/ca/netReadCopyIO_IL.h b/src/ca/netReadCopyIO_IL.h
index ce1ba9f5d..5d3a4d03f 100644
--- a/src/ca/netReadCopyIO_IL.h
+++ b/src/ca/netReadCopyIO_IL.h
@@ -28,5 +28,4 @@ inline void netReadCopyIO::operator delete ( void *pCadaver, size_t size )
     netReadCopyIO::freeList.release ( pCadaver, size );
 }
 
-
 #endif // netReadCopyIO_ILh
diff --git a/src/ca/netReadNotifyIO.cpp b/src/ca/netReadNotifyIO.cpp
index 304833808..f73c45041 100644
--- a/src/ca/netReadNotifyIO.cpp
+++ b/src/ca/netReadNotifyIO.cpp
@@ -16,18 +16,14 @@
 tsFreeList < class netReadNotifyIO, 1024 > netReadNotifyIO::freeList;
 
 netReadNotifyIO::netReadNotifyIO ( nciu &chan, cacNotify &notifyIn ) :
-    cacNotifyIO ( notifyIn ), baseNMIU ( chan )
-{
-}
+    cacNotifyIO ( notifyIn ), baseNMIU ( chan ) {}
 
-netReadNotifyIO::~netReadNotifyIO () 
-{
-    // private NOOP forces pool allocation
-}
+// private NOOP forces pool allocation
+netReadNotifyIO::~netReadNotifyIO () {}
 
-void netReadNotifyIO::destroy ()
+void netReadNotifyIO::uninstall ()
 {
-    this->baseNMIU::destroy ();
+    this->chan.getPIIU ()->uninstallIO ( *this );
 }
 
 void netReadNotifyIO::completionNotify ()
diff --git a/src/ca/netSubscription.cpp b/src/ca/netSubscription.cpp
index 36b94eaba..734459db1 100644
--- a/src/ca/netSubscription.cpp
+++ b/src/ca/netSubscription.cpp
@@ -25,12 +25,14 @@ netSubscription::netSubscription ( nciu &chan, unsigned typeIn, unsigned long co
 
 netSubscription::~netSubscription () 
 {
-    this->chan.unistallSubscription ( *this );
+    // o netiiu lock must _not_ be applied when calling this
+    // o uninstall from channel and IIU occur in uninstall method
+    this->chan.getPIIU ()->subscriptionCancelRequest ( *this, true );
 }
 
-void netSubscription::destroy ()
+void netSubscription::uninstall ()
 {
-    delete this;
+    this->chan.getPIIU ()->uninstallIO ( *this );
 }
 
 class netSubscription * netSubscription::isSubscription ()
diff --git a/src/ca/netSubscription_IL.h b/src/ca/netSubscription_IL.h
index fc01bee23..930f6dd7d 100644
--- a/src/ca/netSubscription_IL.h
+++ b/src/ca/netSubscription_IL.h
@@ -28,7 +28,7 @@ inline void netSubscription::operator delete ( void *pCadaver, size_t size )
     netSubscription::freeList.release ( pCadaver, size );
 }
 
-inline unsigned long netSubscription::getCount ()
+inline unsigned long netSubscription::getCount () const
 {
     if ( this->chan.connected () ) {
         unsigned long nativeCount = chan.nativeElementCount ();
@@ -47,12 +47,12 @@ inline unsigned long netSubscription::getCount ()
     }
 }
 
-inline unsigned netSubscription::getType ()
+inline unsigned netSubscription::getType () const
 {
     return this->type;
 }
 
-inline unsigned netSubscription::getMask ()
+inline unsigned netSubscription::getMask () const
 {
     return this->mask;
 }
diff --git a/src/ca/netWriteNotifyIO.cpp b/src/ca/netWriteNotifyIO.cpp
index cf86e9a29..e8f0dccae 100644
--- a/src/ca/netWriteNotifyIO.cpp
+++ b/src/ca/netWriteNotifyIO.cpp
@@ -25,9 +25,9 @@ netWriteNotifyIO::~netWriteNotifyIO ()
     // private NOOP forces pool allocation
 }
 
-void netWriteNotifyIO::destroy ()
+void netWriteNotifyIO::uninstall ()
 {
-    this->baseNMIU::destroy ();
+    this->chan.getPIIU ()->uninstallIO ( *this );
 }
 
 void netWriteNotifyIO::completionNotify ()
diff --git a/src/ca/netiiu.cpp b/src/ca/netiiu.cpp
index f466db97b..2dcb16b5d 100644
--- a/src/ca/netiiu.cpp
+++ b/src/ca/netiiu.cpp
@@ -95,6 +95,28 @@ void netiiu::disconnectAllChan ( netiiu & newiiu )
     }
 }
 
+//
+// netiiu::destroyAllIO ()
+//
+// care is taken not to not hold the lock while sending event
+// subscription delete ( when the IO is deleted )
+//
+void netiiu::destroyAllIO ( nciu &chan )
+{
+    baseNMIU *pIO;
+    while ( true ) {
+        {
+            epicsAutoMutex autoMutex ( this->mutex );
+            pIO = chan.tcpiiuPrivateListOfIO::eventq.first ();
+            if ( ! pIO ) {
+                break;
+            }
+            pIO->uninstall ();
+        }
+        pIO->destroy ();
+    }
+}
+
 void netiiu::connectTimeoutNotify ()
 {
     epicsAutoMutex autoMutex ( this->mutex );
@@ -133,7 +155,6 @@ bool netiiu::searchMsg ( unsigned short retrySeqNumber, unsigned &retryNoForThis
         status = false;
     }
 
-
     return status;
 }
 
@@ -196,9 +217,8 @@ int netiiu::subscriptionRequest ( netSubscription &subscr, bool )
     return ECA_NORMAL;
 }
 
-int netiiu::subscriptionCancelRequest ( netSubscription &, bool userThread )
+void netiiu::subscriptionCancelRequest ( netSubscription &, bool userThread )
 {
-    return ECA_NORMAL;
 }
 
 int netiiu::installSubscription ( netSubscription &subscr )
@@ -210,19 +230,12 @@ int netiiu::installSubscription ( netSubscription &subscr )
         epicsAutoMutex autoMutex ( this->mutex );
         subscr.channel ().tcpiiuPrivateListOfIO::eventq.add ( subscr );
     }
-    return this->subscriptionRequest ( subscr, true );
-}
-
-void netiiu::unistallSubscription ( netSubscription &subscr )
-{
-    // we must cancel the subscription first so that clean up
-    // is guaranteed to occur if a disconnect occurs beteen 
-    // these two steps
-    this->subscriptionCancelRequest ( subscr, true );
-    {
+    int status = this->subscriptionRequest ( subscr, true );
+    if ( status != ECA_NORMAL ) {
         epicsAutoMutex autoMutex ( this->mutex );
         subscr.channel ().tcpiiuPrivateListOfIO::eventq.remove ( subscr );
     }
+    return status;
 }
 
 void netiiu::hostName ( char *pBuf, unsigned bufLength ) const
@@ -244,4 +257,10 @@ void netiiu::disconnectAllIO ( nciu & )
 
 void netiiu::connectAllIO ( nciu & )
 {
+}
+
+void netiiu::uninstallIO ( baseNMIU &io )
+{
+    epicsAutoMutex autoMutex ( this->mutex );
+    io.channel ().tcpiiuPrivateListOfIO::eventq.remove ( io );
 }
\ No newline at end of file
diff --git a/src/ca/tcpiiu.cpp b/src/ca/tcpiiu.cpp
index 08bd3c350..8acb26075 100644
--- a/src/ca/tcpiiu.cpp
+++ b/src/ca/tcpiiu.cpp
@@ -1758,7 +1758,7 @@ int tcpiiu::subscriptionRequest ( netSubscription &subscr, bool userThread )
     return status;
 }
 
-int tcpiiu::subscriptionCancelRequest ( netSubscription &subscr, bool userThread )
+void tcpiiu::subscriptionCancelRequest ( netSubscription &subscr, bool userThread )
 {
     if ( this->sendQue.flushThreshold ( 16u ) ) {
         if ( userThread ) {
@@ -1771,29 +1771,17 @@ int tcpiiu::subscriptionCancelRequest ( netSubscription &subscr, bool userThread
 
     epicsAutoMutex autoMutex ( this->mutex );
 
-    int status;
-    baseNMIU *pIO = this->ioTable.remove ( subscr );
-    if ( pIO == &subscr ) {
-        status = this->sendQue.reserveSpace ( 16u );
-        if ( status == ECA_NORMAL ) {
-            if ( ! subscr.channel ().verifyConnected ( *this ) ) {
-                status = ECA_DISCONNCHID;
-            }
-            else {
-                this->sendQue.pushUInt16 ( CA_PROTO_EVENT_CANCEL ); // cmd
-                this->sendQue.pushUInt16 ( 0u ); // postsize
-                this->sendQue.pushUInt16 ( static_cast < ca_uint16_t > ( subscr.getType () ) ); // dataType
-                this->sendQue.pushUInt16 ( static_cast < ca_uint16_t > ( subscr.getCount () ) ); // count
-                this->sendQue.pushUInt32 ( subscr.channel ().getSID () ); // cid
-                this->sendQue.pushUInt32 ( subscr.getID () ); // available
-            }
+    int status = this->sendQue.reserveSpace ( 16u );
+    if ( status == ECA_NORMAL ) {
+        if ( subscr.channel ().verifyConnected ( *this ) ) {
+            this->sendQue.pushUInt16 ( CA_PROTO_EVENT_CANCEL ); // cmd
+            this->sendQue.pushUInt16 ( 0u ); // postsize
+            this->sendQue.pushUInt16 ( static_cast < ca_uint16_t > ( subscr.getType () ) ); // dataType
+            this->sendQue.pushUInt16 ( static_cast < ca_uint16_t > ( subscr.getCount () ) ); // count
+            this->sendQue.pushUInt32 ( subscr.channel ().getSID () ); // cid
+            this->sendQue.pushUInt32 ( subscr.getID () ); // available
         }
     }
-    else {
-        status = ECA_BADMONID;
-    }
-
-    return status;
 }
 
 void tcpiiu::lastChannelDetachNotify ()
@@ -1964,22 +1952,22 @@ void tcpiiu::connectAllIO ( nciu &chan )
 {
     epicsAutoMutex autoMutex ( this->mutex );
     if ( chan.verifyConnected ( *this ) ) {
-        tsDLIterBD < baseNMIU > iter = 
+        tsDLIterBD < baseNMIU > pNetIO = 
             chan.tcpiiuPrivateListOfIO::eventq.first ();
-        while ( iter.valid () ) {
-            tsDLIterBD < baseNMIU > next = iter.itemAfter ();
-            class netSubscription *pSubscr = iter->isSubscription ();
+        while ( pNetIO.valid () ) {
+            tsDLIterBD < baseNMIU > next = pNetIO.itemAfter ();
+            class netSubscription *pSubscr = pNetIO->isSubscription ();
             if ( pSubscr ) {
                 this->subscriptionRequest ( *pSubscr, false );
             }
             else {
                 // it shouldnt be here at this point - so uninstall it
-                this->ioTable.remove ( *iter );
-                chan.tcpiiuPrivateListOfIO::eventq.remove ( *iter );
-                iter->exceptionNotify ( ECA_DISCONN, this->pHostName () );
-                iter->destroy ();
+                this->ioTable.remove ( *pNetIO );
+                chan.tcpiiuPrivateListOfIO::eventq.remove ( *pNetIO );
+                pNetIO->exceptionNotify ( ECA_DISCONN, this->pHostName () );
+                pNetIO->destroy ();
             }
-            iter = next;
+            pNetIO = next;
         }
     }
     this->flush ();
@@ -1990,24 +1978,33 @@ void tcpiiu::disconnectAllIO ( nciu &chan )
 {
     epicsAutoMutex autoMutex ( this->mutex );
     if ( chan.verifyConnected ( *this ) ) {
-        tsDLIterBD < baseNMIU > iter = 
+        tsDLIterBD < baseNMIU > pNetIO = 
             chan.tcpiiuPrivateListOfIO::eventq.first ();
-        while ( iter.valid () ) {
-            tsDLIterBD < baseNMIU > next = iter.itemAfter ();
-            class netSubscription *pSubscr = iter->isSubscription ();
+        while ( pNetIO.valid () ) {
+            tsDLIterBD < baseNMIU > next = pNetIO.itemAfter ();
+            class netSubscription *pSubscr = pNetIO->isSubscription ();
+            this->ioTable.remove ( *pNetIO );
             if ( pSubscr ) {
                 this->subscriptionCancelRequest ( *pSubscr, false );
             }
             else {
                 // no use after disconnected - so uninstall it
-                this->ioTable.remove ( *iter );
-                chan.tcpiiuPrivateListOfIO::eventq.remove ( *iter );
-                iter->exceptionNotify ( ECA_DISCONN, this->pHostName () );
-                iter->destroy ();
+                chan.tcpiiuPrivateListOfIO::eventq.remove ( *pNetIO );
+                pNetIO->exceptionNotify ( ECA_DISCONN, this->pHostName () );
+                pNetIO->destroy ();
             }
-            iter = next;
+            pNetIO = next;
         }
     }
 }
 
+void tcpiiu::uninstallIO ( baseNMIU &io )
+{
+    epicsAutoMutex autoMutex ( this->mutex );
+    if ( io.channel ().verifyConnected ( *this ) ) {
+        this->ioTable.remove ( io );
+    }
+    io.channel ().tcpiiuPrivateListOfIO::eventq.remove ( io );
+}
+