Medical interpreter agency: the three delivery modes, the credentials to insist on, and how to brief one

A medical interpreter agency supplies trained interpreters for spoken conversations in a clinical setting, in three delivery modes: on site, where an interpreter attends in person, over the phone, where a call is connected in a minute or two, and video remote, where the interpreter joins on a screen. Most healthcare organisations buy all three from one supplier or two, because each mode suits a different encounter. The agency also handles interpreter recruitment, credential verification, scheduling, confidentiality obligations and the records that prove language assistance was provided.

This page covers choosing, briefing and judging an agency for spoken interpreting. For translation of written documents, which is a separate trade with separate quality controls, see our guide to professional translation agencies.

The three modes, and what each one is for

Mode	Best for	What it needs on your side
On site, in person	Consent conversations, breaking bad news, mental health assessments, long appointments, patients with low vision or hearing, paediatrics	Advance scheduling, a room, and a cancellation policy you can live with
Over the phone	Unscheduled encounters, triage, pharmacy and billing calls, rare languages, after hours	A dual handset or speakerphone, and a dialling card at every point of care
Video remote	Encounters where visual cues matter, sign language, and anything unscheduled where an in person interpreter cannot arrive in time	Stable bandwidth, a mobile cart or tablet, and a tested place to park it

A practical rule used widely in hospitals: schedule on site for the conversations that change a care decision, and keep telephone and video available everywhere so that no encounter ever runs without an interpreter because one could not be booked.

The credentials to ask for by name

Interpreter is not a protected title in most places, so the credential is how you separate a trained healthcare interpreter from a bilingual speaker. Two national certifying bodies in the United States are the ones to name in an RFP, and both publish their own requirements.

• The Certification Commission for Healthcare Interpreters awards the Core Certification Healthcare Interpreter credential, CoreCHI, the CoreCHI Performance credential, CoreCHI-P, and the Certified Healthcare Interpreter credential, CHI. Its own certifications page states that it began sunsetting the CoreCHI credential on 1 January 2025, and that current CoreCHI holders take and pass its ETOE exam to earn CoreCHI-P and remain certified. CCHI describes its certifications as open to healthcare interpreters of any language. Checked 9 October 2026 at cchicertification.org.
• The National Board of Certification for Medical Interpreters awards the Certified Medical Interpreter credential, CMI, with full certification offered in Spanish, Russian, Mandarin, Cantonese, Korean and Vietnamese, and a Hub-CMI credential available to interpreters in other languages who pass the written exam. The board states that it verifies each candidate meets all prerequisites before testing. Checked 9 October 2026 at certifiedmedicalinterpreters.org.

Ask for the credential, the certifying body and the expiry date for every interpreter who will work with you, and ask how the agency verifies them at onboarding and at renewal. For languages where no certification exam exists, ask what the agency does instead: documented training hours in medical interpreting, a language proficiency assessment, and a recorded skills evaluation.

The obligations that sit behind the purchase

Language access in healthcare is a legal duty in the United States, not a courtesy. Title VI of the Civil Rights Act of 1964 and Section 1557 of the Affordable Care Act both bear on it, and the settled practice that follows from them shapes what you buy:

• Language assistance is provided at no cost to the patient.
• Patients are not asked to supply their own interpreter, and family members or minors are not used as the interpreter for a clinical conversation.
• Interpreters are qualified for the setting, which is why the credential question above belongs in the contract.
• The encounter is documented, including the language, the mode and the interpreter identifier, which is a reporting requirement to put on the agency.

Confirm the current text of the applicable rules with your own counsel or compliance team before you write them into a policy, and ask the agency to state in writing how its service supports each point.

Every line that belongs in a rate card

• Per minute rate for telephone interpreting, by language tier, with any minimum billed duration.
• Per minute rate for video remote interpreting, and whether sign language is priced separately.
• Hourly rate for on site work, the minimum booking length, and the increment billed after it.
• Travel time, mileage and parking for on site assignments, with the radius each applies in.
• After hours, weekend and public holiday differentials, and the hour at which each begins.
• Rare language premium, and the list of languages it applies to.
• Cancellation and no show terms by notice period, which is the clause that costs the most in practice.
• Implementation, training and account management, and whether any of it is charged.
• Technology: tablets, carts, app licences, dual handsets, and who owns the hardware.
• Reporting, including whether encounter level data export is included.

The service levels to agree before you sign

Measure	What to specify
Average connect time	Separate targets for your top languages and for everything else, measured in seconds, for both phone and video
Fill rate for scheduled on site work	The share of confirmed bookings attended, with a credible replacement process behind it
Abandonment rate	Calls that never reached an interpreter, reported monthly, because this is where a connect time average hides a problem
Language coverage	The named languages available on demand, and the notice required for everything outside that list
Credential reporting	A current register of the interpreters assigned to you, with credential and expiry
Incident handling	How a quality complaint is logged, investigated and closed, and who sees the outcome

How to test an agency before you commit

• Place live test calls. Three languages, including one uncommon one, at three times of day including an evening. Time each connect yourself rather than reading the average in a slide.
• Run a sample encounter with a clinician present. A nurse or physician who works with interpreters daily will tell you more in ten minutes than a procurement scorecard does in a week.
• Ask for the credential register for the interpreters who would cover your top three languages, with certifying body and expiry dates.
• Read the confidentiality terms. Ask for the business associate agreement, the interpreter confidentiality undertaking, and the policy on recording and note retention.
• Check the integration. If interpreting has to work inside your telehealth platform or be launched from the electronic health record, test it rather than taking the compatibility claim.
• Ask about sign language capacity specifically. It is scheduled differently, it is priced differently, and it is the most common gap in an otherwise good contract.

The medical interpreter agency questions worth an answer

What is the difference between an interpreter and a translator?

Interpreters work with spoken or signed language in real time. Translators work with written text. They are separate skills with separate certifications, and a strong supplier in one is not automatically strong in the other.

Which certification should I require?

Name both national bodies in your requirements and accept either, because the two cover different language sets. CCHI offers CoreCHI, CoreCHI-P and CHI, and the National Board offers CMI in six languages plus Hub-CMI for others. For languages with no exam, require documented training and a recorded skills assessment instead.

Can we use bilingual staff instead of an agency?

Bilingual staff are valuable, and the right way to use them is to assess and designate the ones qualified to interpret, document that assessment, and keep an agency available for every language and every hour they do not cover. Assessment is the step that makes this work.

How fast should a phone interpreter answer?

Set the target yourself in the contract, in seconds, with separate figures for your highest volume languages and for the long tail, and require monthly reporting against it including abandoned calls.

Do we need on site interpreters at all if we have video?

Video covers most unscheduled encounters well. Keep on site capacity for the conversations where it genuinely changes the quality of the exchange: consent, serious diagnoses, mental health assessments, long appointments and encounters where a screen is impractical.

What should the monthly report contain?

Minutes and encounters by language and mode, average and worst case connect time, abandoned calls, fill rate on scheduled bookings, cancellations by notice band, and open quality incidents with status.

Where an interpreter agency is named before anyone calls

A hospital administrator who needs a Spanish and Vietnamese interpreter roster may start by asking an assistant which agencies supply certified medical interpreters. The reply names a few and cites directories, state lists and agency pages.

Your credentials, modes and turnaround from the sections above are only useful if those sources carry them. Ask the question as the administrator would, once per assistant and once per language you serve, and see which agencies are named. AI Knows Us records the answers and the pages cited, so a missing credential can be traced to a missing source.