EU Sovereignty Score
Self-hosted / open sourceTelephony & VoIPHeadquarters: DE

estos: sovereignty score and 8 European alternatives

ProCall is a unified communications and CTI software suite for desktops, offering a client that connects users to business telephone systems and to presence, messaging and call functions. It is developed by estos GmbH in Starnberg, Germany, and is offered in variants for enterprises and for public-sector organisations. The software is deployed on the customer's own computers and servers.

estos GmbH is a German company whose imprint describes it as 'A Gamma company'. Gamma Communications plc, a UK-listed group, completed its acquisition of the STARFACE Group in February 2025, and estos operates within that group. The ultimate owner is therefore located in the United Kingdom, which matters for organisations with strict foreign-ownership requirements. Because the software runs on the customer's own infrastructure, data remains under the control of the organisation that operates it. The website does not state where estos hosts any cloud components or which processing terms apply, so these should be requested before purchase.

See the 8 European alternatives ↓Assess your stack with estos pre-selected
Sovereignty score
80 / 1000 = high exposure
100 = sovereign
  • Jurisdiction SOV-2100
    Headquartered in the EU: European law applies
  • Data residency SOV-3100
    EU-only hosting
  • Cryptographic key sovereignty SOV-380
    Closed source, but self-hostable: encryption keys and runtime under your own control
  • Freedom from lock-in SOV-640
    Closed source: switching requires data migration
  • Source & runtime sovereignty SOV-4 · SOV-680
    Closed source, but self-hostable on your own infrastructure

SOV codes: the matching objective in the European Commission's Cloud Sovereignty Framework. Official source

How the score is calculated

Facts and evidence

Last checked October 11, 2026
HeadquartersDE (EU)Verified by hand
Ultimate parent companyGBVerified by hand
Data hostingSelf-hosted, e.g. in EU (your choice)Verified by hand
Open-sourceNoVerified by hand
GDPR-compliantNoVendor-stated
CategoryTelephony & VoIP
TypeProduct
Websiteestos.de ↗

How we verify · Something wrong? Suggest a correction

Top EU-based & GDPR-compliant alternatives to estos

The European alternatives to estos come from our knowledge base of over 6,200 vendors. We only list vendors headquartered in the EU or the EEA; fully European-owned vendors rank before vendors with a foreign owner. For each alternative you see the country, the open-source status and a short description.

Score per alternative: 0 = high exposure, 100 = sovereign

66 European Telephony & VoIP vendors are in the catalogue. View the whole category · Submit an alternative · View category on the map

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Why digital sovereignty matters with estos

estos is headquartered in DE and therefore falls under European law: the GDPR, NIS2 and the Data Act. No foreign legislation can compel access to your data. The ultimate owner is based in GB. Foreign control undermines part of the certainty a European headquarters offers.

estos runs on infrastructure you choose and control yourself. You decide where the data lives, including fully within the EU if you want — this is not a fixed hosting choice made by the vendor.

estos is closed source, but you run the software yourself on your own infrastructure. The encryption keys and the runtime therefore stay under your own control, though you cannot audit or modify the source code. Ask about export options and open standards to limit software-level lock-in.

What this means for your organisation depends on your whole stack and context. The free assessment weighs estos together with your other vendors and gives a total score, a heatmap and the main risk drivers.

Frequently asked questions

What is the best European alternative to estos?

It depends on your use case. Strong EU alternatives to estos include A1 Telekom Austria, Adversus and Auerswald. On this page you can compare 8 EU alternatives by jurisdiction, data residency and open-source status.

Are there open-source alternatives to estos?

Our list of EU alternatives to estos is mostly commercial options. Browse the category on the map for open-source choices.

Is estos GDPR-compliant and where is the data hosted?

estos is headquartered in DE (EU) and hosts data in EU. That makes estos an EU-sovereign choice in its own right; the EU alternatives on this page are comparable European tools.

Details and sources

Verified by handHeadquarters, owner, hosting locations and licence have been checked by us against public sources. Free of charge and for every vendor, not a paid label. Nothing in this knowledge base is taken over automatically. Last checked on October 11, 2026.

Sources

Public sources used in the latest check of this record.

Compliance evidence

The links below point to the vendor's own public documents. We only record what we found: a missing link means "not found publicly", not "not compliant".

No public compliance evidence has been recorded for this vendor yet. Do you know its DPA or subprocessor list? Something wrong? Suggest a correction

Digital sovereignty in Telephony & VoIP

Telephony & VoIP: Business telephony, VoIP platforms, CPaaS and communication APIs. In this category the choice of vendor determines who has legal access to your data, where that data lives and how easily you can switch later.

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8 European alternatives to estos — GDPR-compliant & EU-hosted · EU Sovereignty Score