Calling contacts,leads, accounts, etc from my Galaxy S3

Calling contacts,leads, accounts, etc from my Galaxy S3

when i am on my galaxy S3 and i am on a website and touch a number, it automatically brings up my phone, ready to make a call to that number. 
Why cant I do that from the zoho website accessed from my galaxy 3??  Why would a service like skype and google voice even be necessary?