YES!
Sutus uses the industry standard SIP protocol for extension connections. The only requirements for a SIP based phone calls are: a SIP extension and credentials (extension and password), and an Internet connection.
Assuming your iPhone has 3G Internet access, you'll need to do two things: 1) Create an extension for your iPhone (in the Administration panel this is called a Soft Phone). 2) Install a SIP client on your iPhone. While there may be several such clients available for varying prices this is one well known client from VNetCorp:
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