From fff5cc4561690081c6626dd2a537b836bda35d43 Mon Sep 17 00:00:00 2001
From: kjagosz <63209438+kjagosz@users.noreply.github.com>
Date: Thu, 8 Jan 2026 19:26:05 +0100
Subject: [PATCH] Add `OnRegisterStateChange` callback to track registration
 state changes.

---
 diago.go                |  2 +-
 register_transaction.go | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/diago.go b/diago.go
index 15edbb0..40dc00b 100644
--- a/diago.go
+++ b/diago.go
@@ -793,13 +793,13 @@ func (dg *Diago) Register(ctx context.Context, recipient sip.Uri, opts RegisterO
 				}
 			}
 		}
-
 		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
 			return err
 		}
 
 		t.expiry = retryAfter
 	}
+	return nil
 }
 
 // Register transaction creates register transaction object that can be used for Register Unregister requests
diff --git a/register_transaction.go b/register_transaction.go
index 45d0d4d..20fba3e 100644
--- a/register_transaction.go
+++ b/register_transaction.go
@@ -42,7 +42,8 @@ type RegisterOptions struct {
 	RetryInterval time.Duration
 	AllowHeaders  []string
 
-	OnRegistered func()
+	OnRegistered          func()
+	OnRegisterStateChange func(bool, error)
 
 	// Useragent default will be used on what is provided as NewUA()
 	// UserAgent         string
@@ -96,12 +97,18 @@ func newRegisterTransaction(client *sipgo.Client, recipient sip.Uri, contact sip
 
 func (t *RegisterTransaction) Register(ctx context.Context) error {
 	if err := t.register(ctx); err != nil {
+		if t.opts.OnRegisterStateChange != nil {
+			t.opts.OnRegisterStateChange(false, err)
+		}
 		return err
 	}
 
 	if t.opts.OnRegistered != nil {
 		t.opts.OnRegistered()
 	}
+	if t.opts.OnRegisterStateChange != nil {
+		t.opts.OnRegisterStateChange(true, nil)
+	}
 	return nil
 }
 func (t *RegisterTransaction) register(ctx context.Context) error {
@@ -187,7 +194,14 @@ func (t *RegisterTransaction) reregisterLoop(ctx context.Context, retry time.Dur
 		expiry := t.expiry
 		err := t.Qualify(ctx)
 		if err != nil {
+			if t.opts.OnRegisterStateChange != nil {
+				t.opts.OnRegisterStateChange(false, nil)
+			}
 			return err
+		} else {
+			if t.opts.OnRegisterStateChange != nil {
+				t.opts.OnRegisterStateChange(true, nil)
+			}
 		}
 
 		if t.expiry != expiry {