How can i take picture to call a number
Google Goggles will do what you are asking. It does an analysis of any taken picture (without saving it to your phone). The results of the analysis will depend upon your picture (for example, if you take a picture of a famous painting it will tell you what the painting is). 

In your case if you take a picture of a phone number, it will highlight the number in the picture allowing you to select and dial it.