Call transcription: how to turn a phone call into text

In short: to turn a phone call into text you first need the recording, and that is the harder part. If you already have a recording, upload the file to a transcription tool. If every call should become text on its own, transcription has to happen on the number side, not on the phone.

Three routes from recording to text

Route	When it makes sense	What it cannot do
Transcription on the phone	you have one call and a phone that can do it	on iPhone, Phone-app transcription supports only some languages; on Android it depends on model, OS version and carrier
Uploading a file to a tool	you already have a recording and want text from it	needs manual work for every call; you must get the recording beforehand
Transcription on the number	calls should turn into text automatically	needs the number to be set up; does not cover calls in messengers

Each route in turn, with what you can realistically expect.

Route 1: transcription on the phone

It is the most convenient route and the least available. Apple added call recording with transcription in iOS 18.1, but transcription in the Phone app supports only selected variants of English, Spanish, Japanese, Korean, Chinese and Portuguese (iOS feature availability, checked 20 October 2026). On Android it varies: Google says Phone-app recording works only on some devices, with some carriers, and not in every country (Google help, checked 20 October 2026), and manufacturers vary their own solutions by sales region.

In practice, you cannot build a process on it, because two people on one team can get different behaviour from the same phone model. We describe these limits in more detail in how to record phone calls.

Route 2: uploading a file

If you already have a recording, from a dictaphone, a conference call or a system that saved it, turning it into text is simple and cheap today. You upload the file and get text; the time depends on the length of the recording and on the tool.

Three things to know before the first time:

Format and length matter. A phone call recording is narrowband, meaning it is stored at lower quality than a microphone recording. The same service will give a clearly weaker result on it than on a podcast.
Separating speakers is a separate feature. Transcription alone gives you a wall of text; assigning sentences to speakers is a different thing and not every tool has it.
Where the file goes. Uploading a customer call to a random service passes that customer's personal data to it. For business calls that is a question of a data processing agreement, not convenience.

Route 3: transcription on the number

The call goes through a number run by a system, so the recording and the text are created on their own for every call, with nothing to remember. The phone-model problem from route 1 also disappears, because nothing depends on the phone or on an Android update.

The price is setting up the number, so this is not a solution for one call. In return it is the only route that works the same way every time and survives a salesperson changing their phone. In Heilo it looks like this: call notes from a company number wait in the panel after the call. Heilo Line gives each salesperson their own Polish +48 company number. Heilo records inbound calls and outbound calls started with "Call via Heilo", and the transcript, summary and tasks reach your CRM through the API, webhooks, Zapier or Make once you set up the integration. See call assistant for sales teams and pricing.

What accuracy to really expect

There is no single number that could honestly be given here, and any such number in a guide is suspect. The result depends on several things at once:

Call quality. A call on a car speaker and a call on a handset are two different inputs.
Number of speakers and talking over each other. Overlapping voices damage a transcript more than background noise.
Proper names, addresses, numbers. Most errors appear there, and these are usually the very reason we want the text.
Length. The longer the call, the greater the chance that something drifts in the middle.

A reasonable expectation: the text will be good for searching and for recalling what was agreed, and it will not be a document you can sign off without reading. The recording remains the source of truth, not the transcript. Heilo keeps the recording for 365 days by default and then deletes it, while the transcript stays, so check important agreements in the recording before that.

To check accuracy on your own team's calls, run a structured test on a sample of recordings and score names, amounts and dates separately.

Names, numbers and inflected languages

In languages with rich inflection, such as Polish, one name appears in several forms, and the system has to recognise them as one. Add numerals, industry abbreviations and company names that do not look like ordinary words.

Practical effects you will see right away:

Surnames and company names need correction more often than the rest of the text.
Amounts and dates are worth checking in the recording before you rely on them.
Short confirmations such as "mm-hm" are sometimes dropped, and sometimes they carry the agreement.

That is why, for customer calls, it is more sensible to treat a transcript as a map of the recording, which lets you find the moment an agreement was made, than as a replacement for listening.

When text alone is not enough

In a company the problem is rarely the lack of text. The problem is that the text sits apart from the contact, the deadline and the task that came out of the call. Three weeks later nobody remembers which file to look in.

Useful transcription is the kind that lands where you work: attached to a contact, with agreements and a next step extracted, available to the whole team, also for calls nobody answered. Heilo Voicemail turns messages left after missed calls into text once you set up carrier forwarding (voicemail to text).

Summary

Turning a call into text stopped being the hard part long ago. The hard part comes earlier, in getting a recording that on many phones cannot be made, and later, in making sure the text does not end up in a folder nobody opens. For one call, uploading a file to a tool is enough. For a company, what matters is that text appears on its own and lands where the customer's case is.

Want transcription to happen automatically on every call to a company number? See: Business call recording.

FAQ

Can I upload a customer call recording to any transcription service?

Technically yes, but legally it passes a customer's personal data to an outside party. For business calls you need a data processing agreement and to know where the data is processed. We covered the obligations around recording separately: business call recording laws.

Does transcription work live, during the call?

Sometimes it is available, but for a phone call it is rarely what you actually need. Live text is hard to read while talking; a summary after the call is more useful.

Why does transcription miss names and amounts?

Because these are words a model cannot guess from context as easily as ordinary sentences, and a phone recording is narrowband. They are both the most common place for errors and the most common reason we want the text, so check exactly those passages in the recording.

Can I transcribe WhatsApp calls?

That is a separate problem, because such a call does not go through the phone network and cannot be recorded in a way you can rely on. We covered it in recording WhatsApp, Messenger and Telegram calls.

How long does transcription take?

For an uploaded file it depends on the length of the recording and the tool. In Heilo processing starts automatically when the call ends, and the recording, transcript and summary appear in the panel shortly after. We do not promise a specific time.