diff --git a/dialog_client.go b/dialog_client.go
index 85dde7e..ab982c5 100644
--- a/dialog_client.go
+++ b/dialog_client.go
@@ -36,6 +36,19 @@ func (s *DialogClient) loadDialog(id string) *DialogClientSession {
 	return t
 }
 
+func (s *DialogClient) MatchDialogRequest(req *sip.Request) (*DialogClientSession, error) {
+	id, err := sip.UACReadRequestDialogID(req)
+	if err != nil {
+		return nil, errors.Join(err, ErrDialogOutsideDialog)
+	}
+
+	dt := s.loadDialog(id)
+	if dt == nil {
+		return nil, ErrDialogDoesNotExists
+	}
+	return dt, nil
+}
+
 // NewDialogClient provides handle for managing UAC dialog
 // Contact hdr must be provided for correct invite
 // In case handling different transports you should have multiple instances per transport
@@ -59,7 +72,7 @@ func (e ErrDialogResponse) Error() string {
 // Invite sends INVITE request and creates early dialog session.
 // You need to call WaitAnswer after for establishing dialog
 // For passing custom Invite request use WriteInvite
-func (dc *DialogClient) Invite(ctx context.Context, recipient sip.Uri, body []byte, headers ...sip.Header) (*DialogClientSession, error) {
+func (c *DialogClient) Invite(ctx context.Context, recipient sip.Uri, body []byte, headers ...sip.Header) (*DialogClientSession, error) {
 	req := sip.NewRequest(sip.INVITE, recipient)
 	if body != nil {
 		req.SetBody(body)
@@ -68,13 +81,13 @@ func (dc *DialogClient) Invite(ctx context.Context, recipient sip.Uri, body []by
 	for _, h := range headers {
 		req.AppendHeader(h)
 	}
-	return dc.WriteInvite(ctx, req)
+	return c.WriteInvite(ctx, req)
 }
 
-func (dc *DialogClient) WriteInvite(ctx context.Context, inviteRequest *sip.Request) (*DialogClientSession, error) {
-	cli := dc.c
+func (c *DialogClient) WriteInvite(ctx context.Context, inviteRequest *sip.Request) (*DialogClientSession, error) {
+	cli := c.c
 
-	inviteRequest.AppendHeader(&dc.contactHDR)
+	inviteRequest.AppendHeader(&c.contactHDR)
 
 	// TODO passing client transaction options is now hidden
 	tx, err := cli.TransactionRequest(ctx, inviteRequest)
@@ -92,23 +105,17 @@ func (dc *DialogClient) WriteInvite(ctx context.Context, inviteRequest *sip.Requ
 			ctx:           ctx,
 			cancel:        cancel,
 		},
-		dc:       dc,
+		dc:       c,
 		inviteTx: tx,
 	}
 
 	return dtx, nil
 }
 
-func (dc *DialogClient) ReadBye(req *sip.Request, tx sip.ServerTransaction) error {
-	callid := req.CallID()
-	from := req.From()
-	to := req.To()
-
-	id := sip.MakeDialogID(callid.Value(), from.Params["tag"], to.Params["tag"])
-
-	dt := dc.loadDialog(id)
-	if dt == nil {
-		return fmt.Errorf("callid=%q: %w", callid.Value(), ErrDialogDoesNotExists)
+func (c *DialogClient) ReadBye(req *sip.Request, tx sip.ServerTransaction) error {
+	dt, err := c.MatchDialogRequest(req)
+	if err != nil {
+		return err
 	}
 
 	dt.setState(sip.DialogStateEnded)
diff --git a/dialog_server.go b/dialog_server.go
index c4e9dbd..f8717a0 100644
--- a/dialog_server.go
+++ b/dialog_server.go
@@ -27,6 +27,19 @@ func (s *DialogServer) loadDialog(id string) *DialogServerSession {
 	return t
 }
 
+func (s *DialogServer) MatchDialogRequest(req *sip.Request) (*DialogServerSession, error) {
+	id, err := sip.UASReadRequestDialogID(req)
+	if err != nil {
+		return nil, errors.Join(ErrDialogOutsideDialog, err)
+	}
+
+	dt := s.loadDialog(id)
+	if dt == nil {
+		return nil, ErrDialogDoesNotExists
+	}
+	return dt, nil
+}
+
 // NewDialogServer provides handle for managing UAS dialog
 // Contact hdr must be provided for responses
 // Client is needed for termination dialog session
@@ -68,36 +81,21 @@ func (s *DialogServer) ReadInvite(req *sip.Request, tx sip.ServerTransaction) (*
 
 // ReadAck should read from your OnAck handler
 func (s *DialogServer) ReadAck(req *sip.Request, tx sip.ServerTransaction) error {
-	id, err := sip.MakeDialogIDFromRequest(req)
+	dt, err := s.MatchDialogRequest(req)
 	if err != nil {
-		return errors.Join(ErrDialogOutsideDialog, err)
-	}
-
-	dt := s.loadDialog(id)
-	if dt == nil {
-		// res := sip.NewResponseFromRequest(req, sip.StatusCallTransactionDoesNotExists, "Call/Transaction Does Not Exist", nil)
-		// if err := tx.Respond(res); err != nil {
-		// 	return err
-		// }
-		return ErrDialogDoesNotExists
+		return err
 	}
 
 	dt.setState(sip.DialogStateConfirmed)
-
 	// Acks are normally just absorbed, but in case of proxy
 	// they still need to be passed
 	return nil
 }
 
-// ReadAck should read from your OnBye handler
+// ReadBye should read from your OnBye handler
 func (s *DialogServer) ReadBye(req *sip.Request, tx sip.ServerTransaction) error {
-	id, err := sip.MakeDialogIDFromRequest(req)
+	dt, err := s.MatchDialogRequest(req)
 	if err != nil {
-		return err
-	}
-
-	dt := s.loadDialog(id)
-	if dt == nil {
 		// https://datatracker.ietf.org/doc/html/rfc3261#section-15.1.2
 		// If the BYE does not
 		//    match an existing dialog, the UAS core SHOULD generate a 481
@@ -106,7 +104,7 @@ func (s *DialogServer) ReadBye(req *sip.Request, tx sip.ServerTransaction) error
 		// if err := tx.Respond(res); err != nil {
 		// 	return err
 		// }
-		return ErrDialogDoesNotExists
+		return err
 	}
 	// Make sure this is bye for this dialog
 	if req.CSeq().SeqNo != (dt.lastCSeqNo + 1) {
diff --git a/sip/sip.go b/sip/sip.go
index d38716a..cff1fbb 100644
--- a/sip/sip.go
+++ b/sip/sip.go
@@ -63,37 +63,44 @@ func DefaultPort(transport string) int {
 	}
 }
 
+// MakeDialogIDFromMessage creates dialog ID of message.
+// Use UASReadRequestDialogID UACReadRequestDialogID for more specific
+// returns error if callid or to tag or from tag does not exists
 func MakeDialogIDFromRequest(msg *Request) (string, error) {
-	var callID, innerID, externalID string = "", "", ""
-	if err := getDialogIDFromMessage(msg, &callID, &innerID, &externalID); err != nil {
+	return UASReadRequestDialogID(msg)
+}
+
+// MakeDialogIDFromResponse creates dialog ID of message.
+// returns error if callid or to tag or from tag does not exists
+func MakeDialogIDFromResponse(msg *Response) (string, error) {
+	var callID, toTag, fromTag string = "", "", ""
+	if err := getDialogIDFromMessage(msg, &callID, &toTag, &fromTag); err != nil {
 		return "", err
 	}
-	return MakeDialogID(callID, innerID, externalID), nil
+	return MakeDialogID(callID, toTag, fromTag), nil
 }
 
-func MakeDialogIDFromResponse(msg *Response) (string, error) {
-	var callID, innerID, externalID string = "", "", ""
-	// TODO switching this fields make no sense?
-	if err := getDialogIDFromMessage(msg, &callID, &innerID, &externalID); err != nil {
+// UASReadRequestDialogID creates dialog ID of message if receiver has UAS role.
+// returns error if callid or to tag or from tag does not exists
+func UASReadRequestDialogID(msg *Request) (string, error) {
+	var callID, toTag, fromTag string = "", "", ""
+	if err := getDialogIDFromMessage(msg, &callID, &toTag, &fromTag); err != nil {
 		return "", err
 	}
-	return MakeDialogID(callID, innerID, externalID), nil
+	return MakeDialogID(callID, toTag, fromTag), nil
 }
 
-// MakeDialogIDFromMessage creates dialog ID of message.
+// UACReadRequestDialogID creates dialog ID of message if receiver has UAC role.
 // returns error if callid or to tag or from tag does not exists
-// Deprecated! Will be removed
-func MakeDialogIDFromMessage(msg Message) (string, error) {
-	switch m := msg.(type) {
-	case *Request:
-		return MakeDialogIDFromRequest(m)
-	case *Response:
-		return MakeDialogIDFromResponse(m)
+func UACReadRequestDialogID(msg *Request) (string, error) {
+	var callID, toTag, fromTag string = "", "", ""
+	if err := getDialogIDFromMessage(msg, &callID, &toTag, &fromTag); err != nil {
+		return "", err
 	}
-	return "", fmt.Errorf("unknown message format")
+	return MakeDialogID(callID, fromTag, toTag), nil
 }
 
-func getDialogIDFromMessage(msg Message, callId, innerId, externalId *string) error {
+func getDialogIDFromMessage(msg Message, callId, toHeaderTag, fromHeaderTag *string) error {
 	callID := msg.CallID()
 	if callID == nil {
 		return fmt.Errorf("missing Call-ID header")
@@ -119,11 +126,11 @@ func getDialogIDFromMessage(msg Message, callId, innerId, externalId *string) er
 		return fmt.Errorf("missing tag param in From header")
 	}
 	*callId = string(*callID)
-	*innerId = toTag
-	*externalId = fromTag
+	*toHeaderTag = toTag
+	*fromHeaderTag = fromTag
 	return nil
 }
 
 func MakeDialogID(callID, innerID, externalID string) string {
-	return strings.Join([]string{callID, innerID, externalID}, "__")
+	return strings.Join([]string{callID, innerID, externalID}, TxSeperator)
 }
diff --git a/sip/transaction_server_tx.go b/sip/transaction_server_tx.go
index ed094a8..07500e1 100644
--- a/sip/transaction_server_tx.go
+++ b/sip/transaction_server_tx.go
@@ -8,8 +8,6 @@ import (
 	"github.com/rs/zerolog"
 )
 
-type FSMfunc func() FSMfunc
-
 type ServerTx struct {
 	commonTx
 	lastAck      *Request
@@ -245,6 +243,9 @@ func (tx *ServerTx) initFSM() {
 	tx.fsmMu.Unlock()
 }
 
+func (tx *ServerTx) State() {
+}
+
 func (tx *ServerTx) delete() {
 	tx.closeOnce.Do(func() {
 		tx.mu.Lock()