diff --git a/src/adn_server/application/routing/helpers.py b/src/adn_server/application/routing/helpers.py
index 402abb4..3204db3 100644
--- a/src/adn_server/application/routing/helpers.py
+++ b/src/adn_server/application/routing/helpers.py
@@ -583,6 +583,9 @@ def _obp_stream_active(st: dict[str, Any], pkt_time: float) -> bool:
     start = float(st.get("START", 0) or 0)
     if start <= 0 or start + 180 < pkt_time:
         return False
+    last = float(st.get("LAST", start) or start)
+    if (pkt_time - last) >= STREAM_TO:
+        return False
     return True
 
 
diff --git a/tests/application/test_slot_contention.py b/tests/application/test_slot_contention.py
index 502dc7c..f37a5c0 100644
--- a/tests/application/test_slot_contention.py
+++ b/tests/application/test_slot_contention.py
@@ -169,6 +169,44 @@ def test_group_voice_tg_collision_rejects_obp_while_hbp_active() -> None:
     )
 
 
+def test_group_voice_tg_collision_rejects_fresh_obp_stream() -> None:
+    """Active OBP leg with recent packets must block a new HBP stream on the same TG."""
+    now = 1_000_000.0
+    obp_stream = bytes_4(0x3E7A0F77)
+    obp_status = {
+        obp_stream: {
+            "TGID": bytes_3(730500),
+            "START": now - 5.0,
+            "LAST": now - 0.1,
+            "RFS": bytes_3(730039266),
+        },
+    }
+    protocols = {"OBP": type("P", (), {"STATUS": obp_status})()}
+    systems = {"OBP": {"MODE": "OPENBRIDGE"}}
+    assert group_voice_tg_ingress_collision(
+        protocols, systems, bytes_3(730500), _STREAM_B, bytes_3(730039256), now,
+    )
+
+
+def test_group_voice_tg_collision_ignores_stale_obp_stream() -> None:
+    """Truncated OBP leg with no recent packets must not block new ingress."""
+    now = 1_000_000.0
+    obp_stream = bytes_4(0x3E7A0F77)
+    obp_status = {
+        obp_stream: {
+            "TGID": bytes_3(730500),
+            "START": now - 60.0,
+            "LAST": now - 45.0,
+            "RFS": bytes_3(730039266),
+        },
+    }
+    protocols = {"OBP": type("P", (), {"STATUS": obp_status})()}
+    systems = {"OBP": {"MODE": "OPENBRIDGE"}}
+    assert not group_voice_tg_ingress_collision(
+        protocols, systems, bytes_3(730500), _STREAM_B, bytes_3(730039256), now,
+    )
+
+
 def test_group_voice_tg_collision_across_hbp_slots() -> None:
     """Active TG on slot 1 must block a new stream on slot 2 (dual-slot OBP peers)."""
     now = 1_000_000.0