We have received the below PEW notification from one of our carriers that we take voice SIMS from. We have been advised by one of our layer 2 suppliers of emergency works to upgrade firmware on their routers to ensure ongoing stability. This will cause short drops in routing during the following periods: 00:00 to 06:00 Fri 13th Feb 00:00 to 04:00 Mon 16th Feb Although traffic should automatically reroute within our core as part of our MPLS infrastructure, some partners may experience disruption to SIM connectivity due to the short heartbeats used on SIM sessions.