Since DSX series are slowly going away and this client had it under intense use for 5 years.
I'm talking about call center with 14 stations running 10 hours a day 6 days a week. Monthly average is 90.000 minutes.
Personally I'm very happy with DSX series and would not touch it unless I have to, they had zero downtime (not counting power outages and provider/user related issues).
I do keep spare parts in stock in case of hardware failure and offering him 4 hour response time.
Is it time to sell him SL1100?
How long DSX might last?
Did he outgrew the capacity of DSX and SL1100 and should be getting something more powerful and more redundant?