diff --git a/.changeset/rare-mugs-complain.md b/.changeset/rare-mugs-complain.md
new file mode 100644
index 00000000..1526eb44
--- /dev/null
+++ b/.changeset/rare-mugs-complain.md
@@ -0,0 +1,5 @@
+---
+"github.com/livekit/protocol": patch
+---
+
+Fix typo in SIP Trunk conversion.
diff --git a/livekit/sip.go b/livekit/sip.go
index 3b3ade6c..840a2b90 100644
--- a/livekit/sip.go
+++ b/livekit/sip.go
@@ -68,8 +68,8 @@ func (p *SIPTrunkInfo) AsOutbound() *SIPOutboundTrunkInfo {
 		Address:      p.OutboundAddress,
 		Transport:    p.Transport,
 		Numbers:      nums,
-		AuthUsername: p.InboundUsername,
-		AuthPassword: p.InboundPassword,
+		AuthUsername: p.OutboundUsername,
+		AuthPassword: p.OutboundPassword,
 	}
 }
 
diff --git a/livekit/sip_test.go b/livekit/sip_test.go
new file mode 100644
index 00000000..c8e05308
--- /dev/null
+++ b/livekit/sip_test.go
@@ -0,0 +1,37 @@
+package livekit
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestSIPTrunkAs(t *testing.T) {
+	t.Run("inbound", func(t *testing.T) {
+		in := &SIPInboundTrunkInfo{
+			SipTrunkId:       "id",
+			Name:             "name",
+			Metadata:         "{}",
+			Numbers:          []string{"+1"},
+			AllowedAddresses: []string{"sip.com"},
+			AllowedNumbers:   []string{"+2", "+3"},
+			AuthUsername:     "user",
+			AuthPassword:     "pass",
+		}
+		got := in.AsTrunkInfo().AsInbound()
+		require.Equal(t, in, got)
+	})
+	t.Run("outbound", func(t *testing.T) {
+		out := &SIPOutboundTrunkInfo{
+			SipTrunkId:   "id",
+			Name:         "name",
+			Metadata:     "{}",
+			Address:      "sip.com",
+			Transport:    1,
+			Numbers:      []string{"+1"},
+			AuthUsername: "user",
+			AuthPassword: "pass",
+		}
+		got := out.AsTrunkInfo().AsOutbound()
+		require.Equal(t, out, got)
+	})
+}