Similar to when you create a quote request with an expiration date, a provider submits their quote with an expiration as well. This prevents the illusion of perpetual pricing on shipments.

When a provider's quote expires, you will not be able to book their quote. However, you can ask the provider to extend the validation of their quotation by clicking "Quote expired, request extension" below the grey "Book" button. 

When changes are made to shipment details, after a provider submitted a quote, providers need to reconfirm the initial quote, or submit a new one. This is done to ensure the quote still aligns with the shipment details. In case a provider needs to confirm, they are informed automatically.