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# Which numbers can I use to register for back in stock WhatsApp alerts?

WhatsApp only allows you to use a number that's not already connected to any other WhatsApp based service. This means that you won't be able to use your existing number that may be connected to the WhatsApp mobile app, WhatsApp for business mobile app, and WhatsApp for business API.

We recommend that you purchase a new mobile number and connect it through our app. In some cases, you may be able to connect a landline/fixed-line number too, but we recommend that you use a mobile number. 

If you want to use your existing WhatsApp number for back in stock alerts, then you need to [permanently delete your current WhatsApp account associated with that number](faq.whatsapp.com/2138577903196467/), and then connect it to our App. Please note that you will permanently lose access to WhatsApp for that number and you won't be able to use that number for any other WhatsApp service. Only back in stock WhatsApp alerts will work for that number.