Calls from unknown numbers have become a common nuisance for many phone users. Some end in commercial offers, others correspond to legitimate customer service, and in certain cases, users report attempts at impersonation by companies or financial entities.
A search for the numbers that accumulate inquiries and warnings reveals very different references. Not all the numbers on this list can be classified as fraudulent: some officially belong to well-known companies, while others are simply flagged by users as commercial, unwanted, or suspicious calls.
Among the numbers that generate the most comments or searches are 600610127, 621146536, 919917750, 652338520, 910203725, 961824716, 914187988, 919120120, 621144595, 919462524, 662866690, 977033470, 917074001, 912443460, 912066666, 912222123, 919611607, 662904971, and 690619836.
A known number does not always mean the call is safe
The number that appears on the screen does not alone prove who is really calling.
INCIBE explains that phone spoofing allows the caller ID to be altered so that the recipient sees a different number from the one originating the communication. This technique is used to impersonate banks, companies, or other well-known organizations.
This explains something that may be confusing: a phone number can actually belong to a company and, at the same time, be associated with attempts at fraud through impersonation. Two cases from this list illustrate this well.
912 222 123: the official Vodafone number that also accumulates complaints
912222123 is not simply a number attributed by a call identification website. Vodafone states on its own customer service page that this is its number for individuals calling from a number not belonging to Vodafone or from abroad, and it identifies it as one of its official channels.
Nevertheless, on collaborative identification pages, there are numerous comments from users describing persistent commercial calls, and other cases where individuals claim to have received communications that appeared to come from Vodafone.
The company itself warns of the existence of phone scams and recommends not to provide personal or banking information during a call if there are doubts about its authenticity. In a suspicious situation, Vodafone advises hanging up and contacting them later through an official channel.
It would not be accurate to call 912222123 a fraudulent number. It can be said that it is an official Vodafone number surrounded by numerous reports, which necessitates distinguishing between a legitimate call from the company and a possible impersonation.
912 066 666: the ING case
A similar situation occurs with 912066666. ING officially confirms that 91 206 66 66 is one of its customer service numbers in Spain, and that +34 912 066 666 is used for calls from abroad.
The problem arises when criminals use impersonation to make the victim believe they are speaking with their bank. The records consulted contain numerous warnings of calls and messages pretending to be from ING, with supposed transfers, charges, or banking movements. Some users describe recordings asking them to press a key to contact a supposed agent.
The number may be authentic, and the call may not be, something that the very concept of spoofing explains. ING cannot be held responsible for a call simply because one of its official numbers appears on the screen.
919 917 750: related to Lowi campaigns
Specialized sources of phone consultation identify 919917750 with telemarketing campaigns from Lowi, the Vodafone brand. The records describe calls aimed at attracting new customers and offers for phone and internet services.
Here, the available information points to the commercial realm, with insufficient basis to present the number as a scam. An unwanted commercial call and a fraudulent call are not the same.
910 203 725: warnings about a supposed teleassistance
910203725 presents more concerning signs. TelefonoSpam collects a report from a person who claims that from this number they identified themselves as the teleassistance service for the so-called red button for the elderly, warning of a possible attempt to obtain personal information.
Clever Dialer also shows user ratings as alleged scams, telemarketing, and identity impersonation, in addition to recording recent calls and blocks.
These data are user reports, not an official resolution attributing a crime to the number holder, so they should be taken as indications and not as an accusation.
600 610 127: SMS that imitate courier companies and banks
600610127 accumulates warnings about SMS that supposedly imitated communications from transport companies. One of the most recent reports describes a message that pretended to come from SEUR and contained a link. Another database collects complaints in which the number would have been used for messages that simulated coming from well-known companies and banking entities.
This is the usual pattern of smishing: the message seeks to provoke a quick reaction, a supposed pending package, an account to update, or a problem with the card, so that the victim clicks a link.
961 824 716: commercial calls from Aquaservice
961824716 is a rather different example. Opinions about this number mention Aquaservice and calls related to the offer or delivery of bottled water. One experience describes a call to confirm the details of a trial delivery, while others label the communications as persistent. Another database collects several negative ratings classifying it as a telemarketer, unwanted call, or possible scam.
User comments are not enough to automatically turn a commercial phone number into a fraudulent one.
914 187 988 and calls claiming to be from Mutua Madrileña
Several user contributions claim that those calling from 914187988 identify themselves as a partner company of Mutua Madrileña and ask for personal data, including ID numbers or dates of birth. One of the published experiences explains that the user refused to provide their ID and the conversation ended there.
The recommendation does not depend on finding out who is behind the number: if someone receives an unexpected call asking for sensitive information, they can hang up and contact the company directly through a phone number obtained from its official website.
919 462 524: numerous calls and commercial activity
919462524 records particularly high activity in some identification services. Clever Dialer collects dozens of recent calls and users who have blocked the number, along with comments about automated calls and commercial communications. Another database classifies it as a telemarketer, unwanted call, robocall, and silent call, and an additional record identifies it with Vodafone as a commercial number.
The available evidence mainly points to commercial activity and calls that some users consider unwanted, without being able to assert that all its calls are fraudulent.
917 074 001: associated with logistics services
User records link 917074001 with a logistics and delivery company, particularly with Zeleris and communications from Movistar. Most of the experiences collected consider it a legitimate number for contacting package recipients. Another collaborative source shows 36 evaluations, with a predominance of classifications as a company and service over those of unwanted calls.
If someone is expecting a package, a call of this type may have a perfectly normal explanation.
912 443 460: the number with the most historical reports
912443460 has a longer history than the rest. A specialized publication already collected in 2019 numerous inquiries from people who had received calls from this phone, describing situations where no operator answered or questions about fiber rates and phone companies.
In a more recent collaborative database, hundreds of references and categories such as aggressive advertising, unknown calls, phone harassment, and telemarketing appear, and users have linked it with Jazztel, Vodafone, and Lowi.
And the rest of the numbers?
The numbers 621146536, 652338520, 621144595, 977033470, 919611607, 662904971, and 690619836, as well as 919120120 and 662866690, also appear in searches and identification services, but with much more limited or contradictory public information. It would not be rigorous to attribute them to a specific company or label them as fraudulent just for appearing on a list of suspicious numbers.
919120120, for example, accumulates evaluations that classify it mostly as a company, although there are also records as an unwanted call, silent call, and telemarketer. 662866690 presents a large number of positive ratings (262 against three negative in the consulted source), most linked to company or service, along with some references to call centers and automated calls.
These two cases show why a list of "spam numbers" should not be read as an official list of fraudulent phones.
Madrid concentrates a good part of the numbers, but the prefix does not prove the origin
Several phones on the list start with 91 or 919, a geographical numbering associated with Madrid. That a number has a Madrid prefix does not mean that the caller is physically in Madrid: virtual switchboards and, above all, spoofing, make the number displayed on the screen not sufficient proof of the real origin of the communication, something that INCIBE itself warns about in its information on caller ID spoofing. Speaking of "calls from Madrid" can be misleading if taken literally.
Spanish regulations are tightening the identification of calls
The problem of commercial calls and impersonation is not resolved solely with applications to block phones. The CNMC is developing new measures to differentiate commercial calls from customer service communications: in April 2026, it explained that commercial calls must be identified using a specific range, 400, while customer service will use free, geographical, or short numbers from operators. In July 2026, it also recorded the initial assignment of numbering in that range 400.
The goal is for the consumer to more easily distinguish a commercial call from a customer service communication before answering.
What to do if you receive a call from one of these numbers
The most important thing is not to rely solely on the identifier that appears on the screen. If the caller asks for passwords, codes received via SMS, banking data, complete card numbers, or other sensitive information, it is prudent to hang up and contact the supposed company through an official channel.
It is also advisable to keep screenshots, SMS, and any other data that help document a possible scam. In the case of unwanted commercial calls, the user can block the number and report the incident to the relevant authorities or companies.
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