Lias:
Buried somewhere deep in the bowels of the UFB Services Agreement, you'll find that Chorus basically reserve the right to do maintenance any time they feel like, but will try and keep it between "11pm and 6am". At a previous employer with an extremely large WAN, this was the bane of the network team, because apparently even for very large corporate customers you can't get Chorus to agree a fixed schedule (e.g. Only doing maintenance on the first Monday of the month, and telling the customer in advance).
Hi Lias, all service providers have access to Chorus networks events information which will keep them informed on upcoming, planned or unplanned work.
With scheduled maintenance, we always try and work with individuals to pick the best time for work to be carried out. When it comes to multiple users sharing network infrastructure, a fixed schedule that everyone can agree on would be any network engineers dream! It's hard to even get a group of four people to agree on where they'll be going for lunch or dinner. ^MIke