Need to autofill Mobile Phone field in the Quick create Contact window from query string using javascript

Hello Everyone,

    I Need to autofill Mobile Phone field in the Quick create Contact window from query string using javascript.

        Problem I am facing to do this is that window.location.href in the javascript function which I am calling on quick create contact form load is returning "https://CRMURL/form/ClientApiWrapper.aspx?ver=1047049190"

but actual url in the browser is 

https://CRMURL/main.aspx?etn=incident&pagetype=entityrecord&extraqs=mobilephone%3D4564748998%26customerid%3D380c2465-03ad-e711-80d7-005056b44c23%26customeridtype%3Dcontact#761510344

So, I am not sure about anyother way to do this. Please let me know if anyone having idea about it.

Thanks

Yogesh