Legal: This is meant to be a guide, and is in no way intended to tell you what your maximum costs would be while using EC2. It’s your responsibility to double check all my math, but as far as I know, I got it right (all math was double checked using iBeast’s bandwidth calculator at http://www.ibeast.com/content/tools/band-calc.asp). Your actual usage will determine what you are billed. This guide only outlines the charges you’ll rack up with EC2, NOT your Voip carrier. You need to keep in mind that all time used to a carrier will be billed based on their guidelines, and are not included in these calculations.
Ok, now that we have all the fine print out of the way….
Amazon charges for EC2 services based on a few a factors.
- How long you run your server
- what server size (hardware, cpu, memory) you select
- How much bandwidth you use (including how many calls you run through your system.)
My assumption is that most people are going to run their machine as a small image. If you run anything other than the small, make sure you have your calculator and checkbook ready.
Small Instance (Default) 1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit), 160 GB of instance storage, 32-bit platform
Pricing for the small image is:
- $0.10 per hour
- All Data Transfer In $0.10 per GB
- First 10 TB per Month Out $0.17 per GB
So, if you’re running your PBX non-stop, you’re looking at a base cost of about $75 per month. Variable costs are going to be based on the bandwidth you use.
All calls will use bandwidth. Make sure to count the data used by your trunk to your carrier, and your route to your endpoint. I’m going to assume you’re using ulaw for the full path, with maximum data usage on the calls for the entire time.
- Ec2 to carrier = 85k
- Ec2 to endpoint = 85k
85kbit + 85kbit = 170kbit/sec = 21.25kB/sec = 1275kB/min = 1.24megs/min
Each minute of your call will use about 1.2 megs, by my calculation, which would be 803 minutes per gig. ½ of the data would be data in and the other ½ would be data out, so the cost would be $0.135 per every 803 minutes you use, or 5,900 minutes per $1.
I find EC2 charges to be very reasonable, and much lower than hosted “root” servers which come with contracts, bandwidth caps, and overage fees. Your needs will vary from mine, so make sure you know what you’re getting yourself in to!