A normal SMS is sent and forgotten. A certified message generates an evidence file: what was sent, to which number, when the network accepted it, when the link was opened, when the full content was read and —if a signature is requested— who completed it with a one-time code. Each event is chained by hash to the previous one and the whole is closed with a qualified time stamp issued by an external authority. The result is an evidence PDF with its public verification code: anyone can check it against the file, without an account and without asking our permission.
The strength of a certificate is not in the paper: it is in every statement having behind it a record that cannot be rewritten.
When the send is created, the SHA-256 hash of the full content is calculated and the file is opened. From then on, changing a comma of the text would break the chain: what the recipient reads is, demonstrably, what was sent.
Sending, acceptance by the network, delivery report, opening of the link, reading of the content, every signature attempt: each event is recorded with the date and time to the millisecond and with the hash of the previous event inside its own. It is an append-only chain: nothing can be deleted or inserted without it showing.
The evidence PDF is closed with a qualified time stamp from AC Camerfirma, S.A., and the whole chain is also anchored every night with a stamp over the day's digest. Not even we could backdate a file without the stamp giving it away.
The certificate that signs our stamps: «AC CAMERFIRMA QUALIFIED TSU - 2024», published in the Spanish trusted list as a qualified time-stamping service with “granted” status.
Not all time stamps are worth the same. Just any technical stamp proves little; a qualified electronic time stamp —the one in art. 42 of the eIDAS Regulation, issued by a provider on the European Union trusted list— enjoys by law the presumption of the accuracy of the date and time it indicates and of the integrity of the data to which it is bound (art. 41.2 of the eIDAS Regulation).
SMSverifica files are stamped with the qualified TSU of AC Camerfirma, S.A., a Spanish certification authority of the chambers of commerce system. And we do not ask you to take our word for it: the signing certificate of every stamp can be checked against the trusted list published by the Spanish State (tsl.digital.gob.es, referenced by the Commission's European list), which is the official source of which providers issue qualified stamps. We ourselves run that check every night: if one day the service were no longer listed as granted, our certificates would stop invoking the presumption that same day, because an evidential document that claims too much is worth less than one that claims just enough.
This is not legal advice: it is the map of the rules that support —and limit— what a certified message can prove. All the references can be checked in the Spanish Official Gazette (BOE) and in EUR-Lex.
The Regulation distinguishes two planes that should not be mixed up. The electronic registered delivery service (art. 3.36) is the service that evidences the sending and receipt of data between third parties; data sent and received using such a service shall not be denied legal effect and admissibility as evidence solely on the grounds that it is in electronic form (art. 43.1). The stronger presumption of art. 43.2 —integrity, sending and receipt presumed— is reserved for the qualified electronic registered delivery service (art. 3.37), which requires the additional requirements of art. 44 and the corresponding supervision. SMSverifica currently provides the non-qualified service, and we say so here and in the PDF itself.
The time stamp belongs to the other plane, and there it does apply: the qualified electronic time stamp of art. 42 enjoys the presumption of the accuracy of the date and time and of the integrity of the stamped data (art. 41.2). That presumption does cover our files, because the stamp is issued by a qualified provider on the trusted list.
Law 6/2020 of 11 November, regulating certain aspects of electronic trust services, refers the effectiveness of electronic documents to the procedural rules (art. 3). Under the Spanish Civil Procedure Act (LEC), electronic documents are admitted as evidence under arts. 299.2 and 382 to 384, and art. 326.3 governs what happens when the other party challenges them. The most useful piece is art. 326.4 LEC (introduced by Law 6/2020 itself): if the challenged document is backed by a qualified trust service —such as the time stamp on our files—, a report can be requested from the provider and the presumption in favour of the document applies, shifting to the challenger the burden of rebutting it. For electronic contracting, art. 24 of the LSSI (Law 34/2002) also expressly admits the electronic medium in which a contract is recorded as documentary evidence.
The leading judgment on messaging is Spanish Supreme Court judgment STS 300/2015 of 19 May (Criminal Chamber, rapporteur Manuel Marchena): it warned of the risk of manipulation of instant-messaging “screenshots” and required, when the conversation submitted is challenged, evidence proving its authenticity and integrity —typically an expert report—. In other words: the evidential problem of a single message is not its admission, it is surviving the challenge. A file with the content fixed by hash before sending, the events chained and the whole under a qualified stamp exists precisely for that moment: it does not provide a screenshot, it provides the verifiable technical trail the judgment finds missing. The final assessment always belongs to the judge (art. 326 LEC); what the file does is reach that assessment with the burden of proof on the right side.
If you are going to base an important claim on a certified file, validate the strategy with your lawyer: the references on this page are real and verifiable, but applying them to your specific case is their job.
The limits, up front, like everything else on this website. Certified messaging is available only to Spain (+34). It is a non-qualified electronic registered delivery service (art. 3.36 eIDAS): the presumption of art. 43.2 does not apply to it, and what it does carry is the qualified time stamp with its presumption under art. 41.2. The recipient's signature with a one-time code is a simple electronic signature, not a qualified one. And the evidential weight of the whole is decided by a judge, not by a marketing page.
Certifying is a surcharge on top of the channel price, the same for all three: €0.25 per certified message (amounts excl. VAT). A certified SMS to Spain is €0.328: the text carries the link to the content and the expiry date, does not fit in a single SMS and takes two —€0.039 each— plus the €0.25 surcharge. By WhatsApp, which is not split, it is €0.255, and by Telegram €0.26. All itemised in your history. The full details are on the pricing page; the integration, with two endpoints, in the REST API.