QC-Phone privacy policy

Last updated: 7 November 2026

This policy applies to the QC-Phone app for iPhone and iPad from version 1.7. For the quadchroma.tech website, the QuadChroma app, purchases through Paddle, the licence server and the customer account, the QuadChroma privacy policy applies.

1. Controller

Robert Brandt, trading as QuadChroma
Schenkenberger Str. 3a
04509 Delitzsch
Germany
E-mail about QC-Phone: social@quadchroma.tech · general: hello@quadchroma.tech

2. The essentials

• The app itself sends QuadChroma no data: no usage data, device identifiers, contacts, call content or crash reports. There is no QuadChroma account, no QuadChroma server, no push service, no advertising, no analytics or tracking service and no third-party component that sends data. The app never contacts quadchroma.tech on its own.
• Calls and the optional message and balance requests go directly between your device and the provider you chose yourself (sections 3 to 5). That provider processes the data as a controller in its own right.
• Everything else stays on your device: history, favourites, notes, recordings and credentials (section 6). Transcription, translation and the assistant run locally (section 7).
• Data only reaches us if you write to us (section 10) and, if you allow it in iOS, as crash logs and aggregated statistics that Apple makes available to us (section 9).

3. Calls through your SIP provider

For calls, QC-Phone connects directly to the SIP provider you set up or to your own router (Homephone on your home network). The provider or router receives: your SIP credentials for signing in, your IP address, the phone numbers, connection data such as time and duration, and the call audio. When interpreting, the translated voice reaches the other person through your provider, like any call audio.

The provider processes this data as a controller in its own right, under its own terms and privacy policy, for example to connect and bill calls. Whether the connection is encrypted (TLS for sign-in and signalling, SRTP for audio) depends on your account. QuadChroma is not involved in these connections and receives nothing from them.

4. Optional provider interfaces

Only if you store your own API credentials for a line does QC-Phone request further data from your account with that provider:

• Telnyx (api.telnyx.com): balance, actual call costs, SMS and MMS texts and conversations of your Telnyx AI assistant. After showing you the change and with your confirmation, the app’s assistant can rename a connection at Telnyx.
• sipgate (api.sipgate.com): balance, SMS and voicemail texts.
• Twilio (api.twilio.com): balance and messages.
• Plivo (api.plivo.com) and Zadarma (api.zadarma.com): balance.

Apart from the confirmed rename at Telnyx, the app only reads. Credentials go only to the respective API server, together with your IP address and the request. Message content stays in memory only, until you export it; cost data is stored on your device. If you remove access in the app, it deletes the local credentials; nothing is deleted at the provider. The respective provider is the controller for the data in your account.

5. Telnyx public rate list

If you load Telnyx’s public rates for a country in the app, QC-Phone queries Telnyx’s public pricing interface without credentials. Telnyx receives your IP address and the country code. Rates you adopt are stored on your device. Telnyx’s terms and privacy policy apply to the request.

6. Storage on your device

• Your device holds the call history, favourites, settings, call notes, tasks, adopted rates and exports. Recordings (M4A) are made only when you start them and confirm that everyone taking part has agreed.
• iOS data protection protects these files; they are excluded from iCloud and device backups.
• SIP credentials, API keys and the optional Wi-Fi name are stored in the iOS Keychain with the setting “this device only”. They are not synced through iCloud Keychain.
• QC-Phone does not add calls to the recents list of the Phone app, so they are not synced through iCloud either.
• Transcripts and loaded messages stay in memory only. Only what you export is stored.

We have no access to this data. You delete recordings, notes and lines in the app; removing a line also deletes its Keychain entries. If you delete the app, iOS removes its files. Remove your lines in the app first if you want the credentials to be gone for certain: iOS may keep Keychain entries after an app is deleted.

7. Transcription, translation and assistant on the device

Transcription, translated captions, interpreting and the assistant run on your device, using Apple’s system features (speech recognition, translation, system voices and Apple Intelligence). There is no cloud speech service and no cloud fallback. The assistant uses only the on-device model, without Private Cloud Compute and without any third-party model; it receives no credentials, account data or transcripts.

Apple downloads the speech models only when you turn on or prepare a feature; Apple’s terms apply to this. For translation, Apple documents possible usage and performance data such as the app’s identifier and the languages involved, but no original or translated text.

Recording, transcription and interpreting require the consent of everyone taking part in the call. QC-Phone asks you to confirm this before it starts; you are responsible for obtaining that consent.

8. Permissions

• Microphone: for calls, the speech test and transcription.
• Local network: for your router and SIP servers on your home network.
• Location “While Using the App”: only if you set your home Wi-Fi for Homephone. iOS requires this permission so that the app can read the Wi-Fi name. QC-Phone does not request location coordinates; the Wi-Fi name stays in the Keychain and is not transmitted.
• Contacts: no access needed. If you pick a number from your contacts, Apple’s picker passes on only that number and the contact’s name.

You can change permissions at any time in the iOS settings.

9. In-app purchase, crash logs and statistics through Apple

Voluntary tip. Apple handles the in-app purchase “Support QC-Phone” through the App Store, not Paddle. Apple is responsible for the purchase and the payment, under Apple’s terms. The app only learns whether the purchase is complete, no payment data. In App Store Connect we see only aggregated sales figures such as number, country and proceeds, no names and no Apple Accounts.

Crash logs and App Analytics. The app itself sends no crash reports. If you have turned on “Share With App Developers” in iOS (Settings › Privacy & Security › Analytics & Improvements), Apple makes crash logs and aggregated statistics on the use of the app available to us through App Store Connect. Apple collects this data under its own terms, not the app. Crash logs describe the technical state at the time of the crash, such as device model, system version, app version and the place in the program code. We use them only to find and fix bugs and do not try to link them to a person. The legal basis is our legitimate interest in a stable app (Art. 6(1)(f) GDPR). How long Apple keeps the data available is up to Apple; copies we download to investigate a bug are deleted once it is fixed. You can turn sharing off in iOS at any time.

More in Apple’s privacy policy.

10. E-mails to us

If you tap our contact address in the app, it only opens your mail app with our address social@quadchroma.tech and a subject. It adds no account data, call content or attachments. We receive your sender address and the content only once you send the e-mail yourself. We process them to reply to you, as described in the section “Requests and e-mails to us” of the QuadChroma privacy policy: the legal basis is our legitimate interest in answering requests (Art. 6(1)(f) GDPR). We keep e-mails and enquiries to us in our mailbox for 3 years after they are closed (the regular limitation period). We keep e-mails from customers for as long as the contract runs and after that for up to 10 years, where tax or commercial law requires it or where we need them to trace what happened. The legal basis for this is Art. 6(1)(b) GDPR while the contract runs, otherwise our legitimate interest in tracing what happened (point (f)), and point (c) where a statutory retention obligation applies. The mailbox is on our own server at STRATO GmbH in Germany, which operates it for us as a processor (Art. 28 GDPR; sending e-mail).

11. Sharing, export and links

TXT, JSON and M4A exports leave the app only through the iOS share sheet, to a destination you choose yourself. Whoever receives them there can keep their own copies. Links to our website, to Instagram, to the providers’ sources and to this policy open in your browser only after you tap them. The terms of the respective site apply there, on Instagram those of Meta.

12. Recipients

Data from the app is received only by:

• your SIP provider or your router (section 3);
• the providers whose interfaces you set up: Telnyx, sipgate, Twilio, Plivo and Zadarma (section 4);
• Telnyx, if you load the public rate list (section 5);
• Apple for the in-app purchase, the speech models and, if you allow it, crash logs and statistics (sections 7 and 9);
• the destinations you choose when sharing (section 11).

If you write to us, your e-mail is stored at STRATO as our processor (section 10). Otherwise we pass on no data unless we are legally obliged to.

Countries outside the EU. If your provider is based outside the European Economic Area, for example in the United States, the data listed goes there from your device. For the United States, the European Commission’s adequacy decision applies to companies taking part in the EU-US Data Privacy Framework (Art. 45 GDPR). Whether your provider takes part or offers other safeguards is stated in its privacy policy. Otherwise the transfer is based on it being necessary for the call or request you want (Art. 49(1)(b) GDPR).

13. Legal bases

Most processing takes place only on your device, under your control and without our access. Where the transfers from the app to your provider, to Telnyx (public rates) and to Apple (speech models) are attributable to us as the provider of the app, the legal basis is providing the features you use in the app (Art. 6(1)(b) GDPR). For data of other people, such as the phone number and voice of the people you call, it is the legitimate interest in enabling the calls and features you want (Art. 6(1)(f) GDPR). Section 9 covers crash logs and statistics, section 10 e-mails.

QC-Phone stores information on your device and reads it there only as far as strictly necessary for the features you use (§ 25(2) no. 2 of the German Telecommunications Digital Services Data Protection Act, TDDDG).

14. Retention

15. Your rights

You have the right of access (Art. 15 GDPR), rectification (Art. 16), erasure (Art. 17), restriction of processing (Art. 18) and data portability (Art. 20). Write to us at social@quadchroma.tech. You manage and delete the data on your device yourself in the app. For data held by your provider, contact the provider; for the in-app purchase and Apple’s data, contact Apple.

16. Right to lodge a complaint

You can lodge a complaint with a data protection supervisory authority. The authority responsible for us is the Saxon Data Protection and Transparency Commissioner (Sächsische Datenschutz- und Transparenzbeauftragte). You can also contact the authority where you live or work or where the alleged infringement took place.

17. Obligation to provide data and automated decisions

You are under no legal or contractual obligation to provide data. Without a SIP account, however, QC-Phone cannot make calls, and without API credentials it cannot load messages or balances. There is no automated decision-making, including profiling (Art. 22 GDPR).

18. Version and changes

This policy was last updated on 7 November 2026 and describes QC-Phone from version 1.7. If the app’s data flows change, we update it; the version on this page applies.