Benefits Of Over-The-Phone Interpretation Services Over-the-phone interpretation (OPI) is a method of interpretation that involves a three-way phone call and requires two-way interpretation. Interpreters facilitate communication between parties who speak different languages. Depending on the situation, the interpreter may be within the same building or office as the client or they may be located remotely. It is common for offices and organizations to need over-the-phone interpreters when they receive many multilingual calls from customers.