In the English-speaking world, a Independent Sales Organization (ISO), also called a Member Service Provider (MSP) is an outside company (not a MasterCard or Visa member) that is contracted by a member bank (each member bank may be a member of Visa or MasterCard, or both) to procure new merchant relationships for the specific bank.

They usually sign up the merchant and explain the terms and rates of a credit card merchant account or cardholder relationship. After signing up, the ISO either submits the paperwork to an acquirer for underwriting or underwrites the account internally. After the merchant is approved, a Processor is then used to actually process the merchant's transactions. In many cases, the ISO is also responsible for providing ongoing customer service after the merchant has been boarded. Technical support or terminal support is generally provided by the Processor, Payment Gateway, or the individual software or hardware vendor providing the payment acceptance device.

ISOs generally recruit Merchant Level Salespeople (MLS) to go out and solicit merchants. MLS are mostly 1099 independent contractors who work for upfront commissions and the right to receive ongoing monthly residuals for the accounts they refer to the ISO.

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