diff --git a/README.md b/README.md
index d931c6b..5b34855 100644
--- a/README.md
+++ b/README.md
@@ -19,10 +19,10 @@ Features:
 - [x] Hangup control on caller
 - [x] Timeouts handling
 - [x] Digest auth
+- [x] DTMF encoder, decoder via RFC4733
 - [ ] Transfers on answer, dial
 - [ ] SDP codec fields manipulating
 - [ ] SDP negotiation fail
-- [ ] DTMF passing
 
 
 Checkout `echome` example to see more. 
diff --git a/media.go b/media.go
index 22da76a..1bdfa2b 100644
--- a/media.go
+++ b/media.go
@@ -1,6 +1,7 @@
 package sipgox
 
 import (
+	"encoding/binary"
 	"fmt"
 	"io"
 	"net"
@@ -11,6 +12,8 @@ import (
 	"github.com/emiago/sipgox/sdp"
 	"github.com/pion/rtcp"
 	"github.com/pion/rtp"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
 )
 
 var (
@@ -18,6 +21,9 @@ var (
 	RTPPortStart  = 0
 	RTPPortEnd    = 0
 	rtpPortOffset = atomic.Int32{}
+
+	RTPDebug  = false
+	RTCPDebug = false
 )
 
 type MediaSession struct {
@@ -34,6 +40,8 @@ type MediaSession struct {
 	// Depending of negotiation this can change
 	// Not thread safe
 	Formats sdp.Formats
+
+	log zerolog.Logger
 }
 
 func NewMediaSession(laddr *net.UDPAddr) (s *MediaSession, e error) {
@@ -42,6 +50,7 @@ func NewMediaSession(laddr *net.UDPAddr) (s *MediaSession, e error) {
 			sdp.FORMAT_TYPE_ULAW, sdp.FORMAT_TYPE_ALAW,
 		},
 		Laddr: laddr,
+		log:   log.With().Str("caller", "media").Logger(),
 	}
 
 	// Try to listen on this ports
@@ -248,7 +257,14 @@ func (m *MediaSession) ReadRTP() (rtp.Packet, error) {
 		return p, err
 	}
 
-	return p, p.Unmarshal(buf[:n])
+	if err := p.Unmarshal(buf[:n]); err != nil {
+		return p, err
+	}
+
+	if RTPDebug {
+		m.log.Debug().Msgf("Recv RTP\n%s", p.String())
+	}
+	return p, err
 }
 
 func (m *MediaSession) ReadRTPWithDeadline(t time.Time) (rtp.Packet, error) {
@@ -291,6 +307,10 @@ func (m *MediaSession) ReadRTCPRaw(buf []byte) (int, error) {
 }
 
 func (m *MediaSession) WriteRTP(p *rtp.Packet) error {
+	if RTPDebug {
+		m.log.Debug().Msgf("RTP write:\n%s", p.String())
+	}
+
 	data, err := p.Marshal()
 	if err != nil {
 		return err
@@ -314,6 +334,12 @@ func (m *MediaSession) WriteRTP(p *rtp.Packet) error {
 }
 
 func (m *MediaSession) WriteRTCP(p rtcp.Packet) error {
+	if RTCPDebug {
+		if sr, ok := p.(fmt.Stringer); ok {
+			m.log.Debug().Msgf("RTCP write: \n%s", sr.String())
+		}
+	}
+
 	data, err := p.Marshal()
 	if err != nil {
 		return err
@@ -369,3 +395,95 @@ func selectFormats(sendCodecs []string, recvCodecs []string) []int {
 	}
 	return formats
 }
+
+// DTMF event mapping (RFC 4733)
+var dtmfEventMapping = map[rune]byte{
+	'0': 0,
+	'1': 1,
+	'2': 2,
+	'3': 3,
+	'4': 4,
+	'5': 5,
+	'6': 6,
+	'7': 7,
+	'8': 8,
+	'9': 9,
+	'*': 10,
+	'#': 11,
+	'A': 12,
+	'B': 13,
+	'C': 14,
+	'D': 15,
+}
+
+func RTPDTMFEncode(char rune) []DTMFEvent {
+	event := dtmfEventMapping[char]
+
+	events := make([]DTMFEvent, 7)
+
+	for i := 0; i < 4; i++ {
+		d := DTMFEvent{
+			Event:      event,
+			EndOfEvent: false,
+			Volume:     10,
+			Duration:   160 * (uint16(i) + 1),
+		}
+		events[i] = d
+	}
+
+	// End events. Took this from linphone example, but not clear why sending this many
+	for i := 4; i < 7; i++ {
+		d := DTMFEvent{
+			Event:      event,
+			EndOfEvent: true,
+			Volume:     10,
+			Duration:   160 * 5, // Must not be increased for end event
+		}
+		events[i] = d
+	}
+
+	return events
+}
+
+// DTMFEvent represents a DTMF event
+type DTMFEvent struct {
+	Event      uint8
+	EndOfEvent bool
+	Volume     uint8
+	Duration   uint16
+}
+
+func (ev *DTMFEvent) String() string {
+	out := "RTP DTMF Event:\n"
+	out += fmt.Sprintf("\tEvent: %d\n", ev.Event)
+	out += fmt.Sprintf("\tEndOfEvent: %v\n", ev.EndOfEvent)
+	out += fmt.Sprintf("\tVolume: %d\n", ev.Volume)
+	out += fmt.Sprintf("\tDuration: %d\n", ev.Duration)
+	return out
+}
+
+// DecodeRTPPayload decodes an RTP payload into a DTMF event
+func DTMFDecode(payload []byte, d *DTMFEvent) error {
+	if len(payload) < 4 {
+		return fmt.Errorf("payload too short")
+	}
+
+	d.Event = payload[0]
+	d.EndOfEvent = payload[1]&0x80 != 0
+	d.Volume = payload[1] & 0x7F
+	d.Duration = binary.BigEndian.Uint16(payload[2:4])
+	// d.Duration = uint16(payload[2])<<8 | uint16(payload[3])
+	return nil
+}
+
+func DTMFEncode(d DTMFEvent) []byte {
+	header := make([]byte, 4)
+	header[0] = d.Event
+
+	if d.EndOfEvent {
+		header[1] = 0x80
+	}
+	header[1] |= d.Volume & 0x3F
+	binary.BigEndian.PutUint16(header[2:4], d.Duration)
+	return header
+}
diff --git a/media_test.go b/media_test.go
index 67aefc3..d059ba9 100644
--- a/media_test.go
+++ b/media_test.go
@@ -25,3 +25,37 @@ func TestMediaPortRange(t *testing.T) {
 	}
 
 }
+
+func TestDTMFEncodeDecode(t *testing.T) {
+	// Example payload for DTMF digit '1' with volume 10 and duration 1000
+	// Event: 0x01 (DTMF digit '1')
+	// E bit: 0x80 (End of Event)
+	// Volume: 0x0A (Volume 10)
+	// Duration: 0x03E8 (Duration 1000)
+	payload := []byte{0x01, 0x8A, 0x03, 0xE8}
+
+	event := DTMFEvent{}
+	err := DTMFDecode(payload, &event)
+	if err != nil {
+		t.Fatalf("Error decoding payload: %v", err)
+	}
+
+	if event.Event != 0x01 {
+		t.Errorf("Unexpected Event. got: %v, want: %v", event.Event, 0x01)
+	}
+
+	if event.EndOfEvent != true {
+		t.Errorf("Unexpected EndOfEvent. got: %v, want: %v", event.EndOfEvent, true)
+	}
+
+	if event.Volume != 0x0A {
+		t.Errorf("Unexpected Volume. got: %v, want: %v", event.Volume, 0x0A)
+	}
+
+	if event.Duration != 0x03E8 {
+		t.Errorf("Unexpected Duration. got: %v, want: %v", event.Duration, 0x03E8)
+	}
+
+	encoded := DTMFEncode(event)
+	require.Equal(t, payload, encoded)
+}
diff --git a/phone.go b/phone.go
index 030172d..dbb802e 100644
--- a/phone.go
+++ b/phone.go
@@ -200,6 +200,9 @@ func (p *Phone) createServerListener(s *sipgo.Server, a ListenAddr) (*Listener,
 			return nil, fmt.Errorf("listen udp error. err=%w", err)
 		}
 
+		// Port can be dynamic
+		a.Addr = udpConn.LocalAddr().String()
+
 		return &Listener{
 			a,
 			udpConn,
@@ -217,6 +220,7 @@ func (p *Phone) createServerListener(s *sipgo.Server, a ListenAddr) (*Listener,
 			return nil, fmt.Errorf("listen tcp error. err=%w", err)
 		}
 
+		a.Addr = conn.Addr().String()
 		// and uses listener to buffer
 		if network == "ws" {
 			return &Listener{
diff --git a/register_transaction.go b/register_transaction.go
index 3f88aec..f5d3082 100644
--- a/register_transaction.go
+++ b/register_transaction.go
@@ -29,8 +29,10 @@ func NewRegisterTransaction(log zerolog.Logger, client *sipgo.Client, recipient
 	// log := p.getLoggerCtx(ctx, "Register")
 	req := sip.NewRequest(sip.REGISTER, recipient)
 	req.AppendHeader(&contact)
-	expires := sip.ExpiresHeader(expiry)
-	req.AppendHeader(&expires)
+	if expiry > 0 {
+		expires := sip.ExpiresHeader(expiry)
+		req.AppendHeader(&expires)
+	}
 	if allowHDRS != nil {
 		req.AppendHeader(sip.NewHeader("Allow", strings.Join(allowHDRS, ", ")))
 	}
diff --git a/sdp_utils.go b/sdp_utils.go
index bebceed..8e9bbaa 100644
--- a/sdp_utils.go
+++ b/sdp_utils.go
@@ -47,13 +47,14 @@ func SDPGenerateForAudio(originIP net.IP, connectionIP net.IP, rtpPort int, mode
 		// "b=AS:84",
 		fmt.Sprintf("c=IN IP4 %s", connectionIP),
 		"t=0 0",
-		fmt.Sprintf("m=audio %d RTP/AVP %s", rtpPort, strings.Join(fmts, " ")),
+		fmt.Sprintf("m=audio %d RTP/AVP %s", rtpPort, strings.Join(fmts, " ")+" 101"),
 		"a=" + string(mode),
 		// "a=ssrc:111222 cname:user@example.com",
 		// "a=rtpmap:0 PCMU/8000",
 		// "a=rtpmap:8 PCMA/8000",
-		// "a=rtpmap:101 telephone-event/8000",
-		// "a=fmtp:101 0-16",
+		// THIS is FOR DTM
+		"a=rtpmap:101 telephone-event/8000",
+		"a=fmtp:101 0-16",
 		// "",
 		// "a=rtpmap:120 telephone-event/16000",
 		// "a=fmtp:120 0-16",