[Swapnasangeetha]

I have got a mobile called lumia 800,since i was unable to download my app I rebooted my mobile and now i could install all the application successfully including watsapp.All the appplication are working well except watsapp.It says that"can't register with this phone number you can only register with the phone number that was last used with whatsapp on this phone".i uninstalled several times and i installed watsapp But,still i could not over come the problem.please help

[abhishek singh21]

it is most likely because you lumia is on a software ( windows phone 7) which is not supported / abandoned by whatsapp this year.
so basically you will have to switch to a new device/OS in order to enjoy whatsapp.

[swapna sangeetha]

Hi,thanks for your answer.As you said mine is windows 7 only
So,now I need to update the software so tell me how do I update the software.

[pkcable]

As per this https://www.whatsapp.com/faq/en/wp/21478428

As of July 1st, 2016, the requirements to begin using WhatsApp on a Windows Phone are the following:
[LIST=1][*]The phone must be running Windows Phone 8 or higher.[*]The phone must have an active Internet connection.[/LIST]

Depending on who you believe it MAY or MAY NOT be possible to update your Lumia 800 to the required 8.1. I have read conflicting reports in my googling. I would also caution you, since your model is an older one and not designed for Win 8.1 or Win 10, even if you CAN get it to install it may run poorly. Do you REALLY want to do this for 1 app? What about going to another messenger platform? Skype, BBM, or Kik?