The main reason we can't provide a static list is that the numbers are constantly changing. All the same number pools are used by hundreds of carries outside of VOIPo. That's why you'll see the same numbers show up at multiple providers.

National VoIP providers typically never keep an internal inventory of any kind and use APIs from all the partners and combine the results. This is mainly because there are just so many rate centers.

Since so many providers are using the same pools, it's very common that a number there now won't be in a hour. That's not always the case but ultimately it happens enough where we have to set it up to immediately purchase a number if someone selects it or else risk it may be gone.

The only way to reserve or hold a number is to purchase it from our carrier partner so without being able to bill the customer in real-time, that can be risky.

With all this being said, we do have a solution coming that's a little different but I think will do what you're asking in a little different way. I'm not going to get into a lot of specifics yet since it's not done and anything could change, but it's an "Order Form Builder" system that will take the order and then direct to a payment URL you provide to complete the order OR you can send customer to your payment/billing system and have it redirect to this to complete the order.