When using the Ding app, you can access the contacts saved on your phonebook by following these steps:

1. Go to the Top-up section.

2. Select Contacts. You'll be prompted to grant the app permission to access your phone's contact list.

3. Choose which contact you want to send your top-up to and continue with the top-up process.

If you'd like to recharge a new phone number and save it for future use, simply add it to your phonebook, and the app will access it from there.