We found this video of how icall use via iphone by installing their voip app.

The iCall app for iPhone is easy to use.

When you open iCall for the first time you will need to set up what kind of plan you’ll be using. If all you want to do is be able to make phone calls one of icall options is completely free. The icall setup for this kind of account consists of making a phone call to a number to confirm what your cell phone number is. Once you’ve done that all you have to do is dial any number to call out over WiFi or the cell network. The great thing is that you can start a call at home on WiFi and then continue it when you leave the house on 3G or EDGE!

Upgrade your icall plan to $10 a month you can get unlimited outgoing and incoming calls to your own private number. Currently, you may find it limited, but icall is constantly expanding it. With this icall facility, you friends are able to get ahold of you at home as well as be able to call out over WiFi. Just have to ensure that you have WiFi set up properly in your home and you will receive a push notification over WiFi that will let you know when you have an incoming call! When you receive the message all you have to do is touch answer to open up iCall and answer the call immediately.

Call quality in icall varies although most are pleased with the calls over iPhone 3GS. Some may experience choppy audio but this is suspected to be due to the memory problems that the 3G has.

This icall app also offers a decent array of features that you would expect. It allows you to use your iPhone contacts list from directly within the icall app, it shows you a list of calls that you’ve made recently and it also offers a voice mail box that is particularly useful if you decide to pay for a personal incoming number.

Basically, in the icall iphone app, the basic service works well and its cheap.

iCall is another voip app that can be downloaded from the App Store. It allows you to link to your Facebook account. After the main start-up screen and accepting the user agreement, iCall will prompt you to select an account type. It offers a variety of accounts including a trial, free-use and paid use. iCall will then place a verification call and your account will be ready to go.