diff --git a/gso/workflows/iptrunk/terminate_iptrunk.py b/gso/workflows/iptrunk/terminate_iptrunk.py
index cd2614c7027e531cea5e1aa482e5b65c439cbb46..33ee86fde6129a05278d8985a3959e2ef945c067 100644
--- a/gso/workflows/iptrunk/terminate_iptrunk.py
+++ b/gso/workflows/iptrunk/terminate_iptrunk.py
@@ -16,6 +16,7 @@ from orchestrator.workflows.steps import (
     unsync,
 )
 from orchestrator.workflows.utils import wrap_modify_initial_input_form
+from pydantic import validator
 
 from gso.products.product_blocks.iptrunk import IptrunkSideBlock
 from gso.products.product_blocks.router import RouterVendor
@@ -23,7 +24,7 @@ from gso.products.product_types.iptrunk import Iptrunk
 from gso.services import infoblox
 from gso.services.netbox_client import NetboxClient
 from gso.services.provisioning_proxy import execute_playbook, pp_interaction
-from gso.utils.helpers import get_router_vendor
+from gso.utils.helpers import get_router_vendor, validate_tt_number
 from gso.utils.workflow_steps import set_isis_to_90000
 
 
@@ -40,6 +41,10 @@ def initial_input_form_generator() -> FormGenerator:
         clean_up_ipam: bool = True
         clean_up_netbox: bool = True
 
+        @validator("tt_number", allow_reuse=True)
+        def validate_tt_number(cls, tt_number: str) -> str:
+            return validate_tt_number(tt_number)
+
     user_input = yield TerminateForm
     return user_input.dict()