At 600 watts running continuously wouldn't that be 432 kWh a month?
Assuming you didn't mean you were running your gaming computer as the server.
At 100 watts that comes out to 72 kWh, in CT where I live rates are waaaay higher then what I calculate your rate to be (around 2.5 cents per kWh)
For me a 100 watt server is about ~$22 a month to run.
Are you sure your paying 2.5 cents per kWh?
Kinda defeats the purpose of a phone...unless you want to only be contacted/updated at some interval you actively choose