In short
Sales-as-a-service, also called outsourced sales, means that an outside team sells your product for you. The team prospects, holds the conversations, runs demos and moves deals toward a signature, while you keep building the product and owning the customer relationship afterwards.
It sits between two other options. You can hire your own salespeople, which is slow and expensive before you know the market. Or you can wait for inbound leads and hope. Outsourced sales gives you active selling without the fixed cost of a team.
What the external team actually does
A good partner does the unglamorous work: building a target list, writing outreach, booking meetings, qualifying interest and following up for as long as it takes. In a market where you have no local presence, they also bring language, context and the right introductions.
Responsibilities should be written down before anyone starts. Who owns the leads, who handles pricing questions, who signs the contract and who supports the customer after the sale are all questions worth answering on paper.
How it is paid
There are three common models. A monthly retainer pays for activity whether or not deals close. A commission pays a percentage of what is sold. A hybrid mixes a small fixed fee with commission.
Commission-only is the easiest model for a founder to say yes to, because nothing is paid until revenue arrives. The percentage and the duration (one-off, first year, or for the lifetime of the customer) is where the real negotiation happens.
When it makes sense
It tends to fit when the product is proven and has a clear buyer, when you want to test a new country or segment without hiring, and when founders are the bottleneck because they are still doing all the selling themselves.
It fits less well when the product is still changing every week, when the pitch cannot be explained in a short conversation, or when you cannot yet say who the customer is. In those cases the first job is learning, and that is best done by the founders.
What to check before you sign
Ask how leads are sourced, how often you will get reports, who owns the contact data, how long the agreement runs and how either side can end it. Ask for the way they would pitch your product in two minutes. If you cannot tell them apart from a generic sales pitch, keep looking.