An SMS number and a rented number both receive text messages, but they are for different needs.
Use an SMS number for a code from one app
Choose the app and country first. Check the current price and availability, then buy the number. Enter it in the app and watch your SpiderOTP order for the message. The number is for the selected purchase, not a phone line you keep permanently.
Rent a number when you need it for longer
When rentals are available, you can keep a number for several days or weeks. The rental period, price and available options are shown after you sign in. A rental is not the same as buying an SMS code for one app.
Check before you pay
Make sure the app, country and price match what you need. No service can promise that another website will send a code or accept a particular number. Check your order for messages and the applicable cancellation options.