i have a customer with 5 location currently and expected to have around 20 locations at a later stage.
each location would host around 50 users except the HQ which have 300 IP phones.
at the HQ i have CCM and at the branches CME.
i am planning to have a 3 digits extensions with another digits for inter office
4xyyy and 5xyyy
x: the branch
yyy: extension at the branch
any one with such experience recommand this setup or other.