In most cases no, you do not need your own IATA number to get started. Many agencies begin by selling the air content that reaches them through our supplier arrangements, which means the ticket is issued under a licensed party while you act as the selling agent. That lets you start taking flight bookings on your site straight away instead of waiting months for your own accreditation to come through.
That said, it does depend on your market and on the supplier. Some countries have local rules about who is allowed to issue tickets or hold customer money for air travel, and some airlines, particularly budget carriers, want a direct relationship with an agency before their fares show up in a search. If you already hold your own accreditation or you have your own negotiated deals with airlines, we can usually connect those to your account instead, which normally gives you better fares and keeps more of the margin with you.
What you will need in every case is a properly registered travel business, an agreed way to settle what you owe for the tickets you issue, and someone on your side who can look after changes, cancellations and customer questions after travel documents are sent. The API takes care of the search, the booking and the ticket, but the care of the customer stays with you.
The best next step is to tell us which country you operate from and which airlines matter most to your customers, and we will confirm what you can sell on day one and what would need your own agreement.