diff --git a/internal/rpc/rtc/signal.go b/internal/rpc/rtc/signal.go
index 89dfeb52d..7ffb40507 100644
--- a/internal/rpc/rtc/signal.go
+++ b/internal/rpc/rtc/signal.go
@@ -216,7 +216,11 @@ func (s *rtcServer) handleInviteInGroup(ctx context.Context, req *rtc.SignalInvi
 	}
 	inv.BusyLineUserIDList = busyUserIDs
 
-	// 从主叫用户资料获取铃声 URL，注入到邀请信息中，被叫方收到后播放主叫方铃声
+	if len(inv.InviteeUserIDList) == len(busyUserIDs) {
+		return nil, errs.ErrNoPermission.WrapMsg("all invitees are busy", "inviteeUserIDList", inv.InviteeUserIDList)
+	}
+
+	// 从主叫用户资料获取铃声 URL，注入到邀请s信息中，被叫方收到后播放主叫方铃声
 	if inviterInfo, err := s.userClient.GetUserInfo(ctx, req.UserID); err == nil && inviterInfo.CallRingtoneURL != "" {
 		inv.CallerRingtoneURL = inviterInfo.CallRingtoneURL
 	}
diff --git a/openim-sdk-core b/openim-sdk-core
new file mode 120000
index 000000000..889d82c06
--- /dev/null
+++ b/openim-sdk-core
@@ -0,0 +1 @@
+../openim-sdk-core-origin
\ No newline at end of file