diff --git a/cosmo/autodesc.py b/cosmo/autodesc.py
index d08801d..3195cdc 100644
--- a/cosmo/autodesc.py
+++ b/cosmo/autodesc.py
@@ -92,7 +92,10 @@ def toDict(self) -> CosmoOutputType | Never:
             )
             | (  # directly attached line has priority
                 {"line": attached_tobago_line.getName()}
-                if attached_tobago_line and self.suppressTenant()
+                # two different cases: either we have to suppress tenant
+                # OR tenant is not defined due to no linked service definition
+                if (attached_tobago_line and self.suppressTenant())
+                or (attached_tobago_line and not attached_tobago_line.hasTenant())
                 else {}
             )
             | (
@@ -100,7 +103,9 @@ def toDict(self) -> CosmoOutputType | Never:
                     "line": attached_tobago_line.getName(),
                     "tenant": attached_tobago_line.getTenantName(),
                 }
-                if attached_tobago_line and not self.suppressTenant()
+                if attached_tobago_line
+                and attached_tobago_line.hasTenant()
+                and not self.suppressTenant()
                 else {}
             )
             | (
diff --git a/cosmo/netbox_types.py b/cosmo/netbox_types.py
index 86f1234..8dc7def 100644
--- a/cosmo/netbox_types.py
+++ b/cosmo/netbox_types.py
@@ -892,29 +892,35 @@ class CosmoTobagoLine(AbstractNetboxType):
     def getBasePath(self):
         return "/plugins/tobago/lines/"
 
-    def _getCurrentLineMetadata(self):
-        return self["version"]
+    def _getCurrentLineMetadata(self) -> dict:
+        return self.get("version", dict())  # should always be present
 
-    def _getCurrentLine(self):
-        return self._getCurrentLineMetadata()["line"]
+    def _getCurrentLine(self) -> dict:
+        return self._getCurrentLineMetadata().get(
+            "line", dict()
+        )  # should always be present
 
-    def _getCurrentTenant(self):
-        return self._getCurrentLineMetadata()["tenant"]
+    def _getCurrentTenant(self) -> dict | None:
+        return self._getCurrentLineMetadata().get("tenant")
+
+    def hasTenant(self) -> bool:
+        return bool(self._getCurrentTenant())  # False on None or empty
 
     def getLineID(self) -> str:
-        return str(self._getCurrentLine()["id"])
+        return str(self._getCurrentLine().get("id"))
 
     def getLineNameLong(self) -> str:
-        return str(self._getCurrentLine()["name_long"])
+        return str(self._getCurrentLine().get("name_long"))
 
     def getName(self) -> str:
         return self.getLineNameLong()
 
-    def getTenantName(self):
-        return self._getCurrentTenant()["name"]
-
-    def getLineStatus(self):
-        return self._getCurrentLineMetadata()["status"]
+    def getTenantName(self) -> str | None:
+        tenant = self._getCurrentTenant()
+        if bool(tenant) and isinstance(tenant, dict):  # type safety
+            return tenant.get("name")
+        else:
+            return None
 
     def getRelPath(self) -> str:
         return urljoin(self.getBasePath(), self.getLineID())
diff --git a/cosmo/tests/test_case_auto_descriptions.yaml b/cosmo/tests/test_case_auto_descriptions.yaml
index 5deb62d..84a58c1 100644
--- a/cosmo/tests/test_case_auto_descriptions.yaml
+++ b/cosmo/tests/test_case_auto_descriptions.yaml
@@ -262,6 +262,94 @@ device_list:
       name: TEST-VLAN-3
       vid: 3
     vrf: null
+  - custom_fields:
+      inner_tag: null
+      outer_tag: null
+    description: null
+    __typename: InterfaceType
+    enabled: true
+    id: '30754'
+    ip_addresses: [ ]
+    connected_endpoints: null
+    attached_tobago_line:
+      __typename: CosmoTobagoLine
+      component_type: CABLE
+      element:
+        description: ''
+        display: cable 000128935
+        id: 39646
+        label: cable 000128935
+        url: https://netbox.example.com/api/dcim/cables/39646/
+      element_id: 93828
+      element_type: dcim.cable
+      id: 5111
+      index: 1
+      termination_a:
+        _occupied: true
+        cable:
+          description: ''
+          display: cable 000128935
+          id: 39646
+          label: cable 000128935
+          url: https://netbox.example.com/api/dcim/cables/39646/
+        description: ''
+        device:
+          description: ''
+          display: TEST0001
+          id: 1747
+          name: TEST0001
+          url: https://netbox.example.com/api/dcim/devices/1747/
+        display: et-0/0/1.4
+        id: 30750
+        name: et-0/0/1.4
+        url: https://netbox.example.com/api/dcim/interfaces/30754/
+      termination_a_id: 92388
+      termination_a_type: dcim.interface
+      termination_b:
+        _occupied: true
+        id: 198209
+        url: https://netbox.example.com/api/dcim/interfaces/192879/
+        display: xe-0/1/4
+        device:
+          id: 39827
+          url: https://netbox.example.com/api/dcim/device/39827/
+          display: TEST0002
+          name: TEST0002
+          description: null
+        name: xe-0/1/4
+        description: "customer A"
+      termination_b_id: 454
+      termination_b_type: dcim.interface
+      version:
+        created: '2025-09-03T11:34:19.643456+01:00'
+        custom_fields: { }
+        id: 2617
+        last_updated: '2025-09-03T11:34:40.819703+01:00'
+        line:
+          display: cl390287
+          id: 9834
+          name: '390287'
+          name_long: cl390287
+          url: https://netbox.example.com/api/plugins/tobago/lines/9834/
+          service: null
+        status: current
+    lag: null
+    mac_address: 94:BF:41:41:41:F4
+    mode: ACCESS
+    mtu: null
+    name: et-0/0/1.4
+    tagged_vlans: [ ]
+    tags:
+      - __typename: TagType
+        name: edge:customer
+        slug: edge_customer
+    type: virtual
+    untagged_vlan:
+      __typename: VLANType
+      id: '8237463'
+      name: TEST-VLAN-4
+      vid: 4
+    vrf: null
   - custom_fields:
       inner_tag: null
       outer_tag: null
diff --git a/cosmo/tests/test_serializer.py b/cosmo/tests/test_serializer.py
index 46ca148..d8f663a 100644
--- a/cosmo/tests/test_serializer.py
+++ b/cosmo/tests/test_serializer.py
@@ -230,6 +230,7 @@ def test_router_interface_auto_description():
     assert {
         "connected_endpoints": [{"name": "combo1", "device": "mikrotik01"}]
     } == json.loads(sd["interfaces"]["et-0/0/0"]["description"])
+
     # auto type description now overrides existing descriptions
     # assert "do not overwrite me!" == sd["interfaces"]["et-0/0/1"]["description"]
     assert {
@@ -238,12 +239,26 @@ def test_router_interface_auto_description():
         "connected_endpoints": [{"name": "combo2", "device": "mikrotik01"}],
         "type": "peering",
     } == json.loads(sd["interfaces"]["et-0/0/1"]["units"][2]["description"])
+
+    # sub interface with line with service, connected endpoint and link peers
+    # should display line info, tenant info, connected_endpoint and type
     assert {
         "line": "cl390287",
         "tenant": "Contoso Ltd.",
         "connected_endpoints": [{"name": "combo2", "device": "mikrotik01"}],
         "type": "customer",
     } == json.loads(sd["interfaces"]["et-0/0/1"]["units"][3]["description"])
+
+    # sub interface with line without service should display line number but not tenant
+    # and/or service information
+    assert {
+        "connected_endpoints": [{"name": "combo2", "device": "mikrotik01"}],
+        "line": "cl390287",
+        "type": "customer",
+    } == json.loads(sd["interfaces"]["et-0/0/1"]["units"][4]["description"])
+
+    # interface with only link_peers and no connected_endpoints should display
+    # link_peer information
     assert {
         "link_peers": [{"name": "port_45", "device": "Panel48673"}],
         "type": "access",