The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Voxvalley Technologies:
Mahek Calls is a mobile dialer or application which makes or receive VoIP calls with minimum IOS version support of 3.2 on Apple Iphone, ipad, ipod and it uses the 3G/Edge/wifi Internet connectivity.Mahek Calls is developed based on the requirements of VoIP Providers business needs.Features :-Mahek Calls uses SIP protocol based for signaling.Mahek Calls Supports all codecs.Mahek Calls run Behind NAT or private IP.User Friendly Interface.Auto Sync of Balance.Real Time Sip status messages.Call History.Loud Speaker.Hold.Address book integration.Compatible with all sip standard switches.It has very efficient implementation of jitter buffer to play voice smoothly.Silent suppression and comfort noise generation has been used to reduce the bandwidth usage, and this makes the dialer more efficient in making VoIP calls.