Calls from unknown numbers continue to be part of the routine for many users. Mobile phones, landline numbers, and unsolicited commercial calls frequently appear in phone identification services and forums where people share their experiences.
Among the numbers that accumulate searches, comments, or reports are 917656887, 917935927, 912777442, 621194355, 650773442, 608881322, 910623457, 691850318, 787999777, 607100122, 4496890139, 919199477, and 914444400.
Not all exhibit the same behaviour, nor is there a basis to assert that all are fraudulent. Some are linked to commercial campaigns or specific companies, while others accumulate warnings from users about persistent calls or possible attempts to deceive.
These are the numbers generating the most inquiries
The list includes both mobile and landline numbers, several of which have the 91 prefix, associated with geographical numbering in Madrid, although this does not mean that the call physically originates from that city.
The included phones are:
- 917656887
- 917935927
- 912777442
- 621194355
- 650773442
- 608881322
- 910623457
- 691850318
- 787999777
- 607100122
- 4496890139
- 919199477
- 914444400
The available public information is uneven. In some cases, there are dozens of user ratings; in others, there are barely enough records to securely identify who is using the line.
917935927: hundreds of searches and warnings related to commercial calls
The 917935927 is one of the phones on this list with the most public information available.
A collaborative database records 36 evaluations, of which 33 are negative, with categories such as automated calls, financial services, debt recovery, telemarketer, and unwanted call. Another specialised page links it to electricity and telephone campaigns: several users claim to have received calls attempting to change their provider.
A previous analysis by TuExperto already collected over 2,000 reports associated with this phone, although it clarified that these were third-party testimonies, not an official identification of the owner.
912777442: a number historically linked to Vodafone
The 912777442 has a broad history of inquiries. ADSLZone analysed the phone in March 2026 and found that identification databases link it to both Vodafone and possible fraudulent calls, without confirmation that the operator still uses that numbering. The outlet also notes that identifying who is calling is not enough to know who is really behind it.
The number had already accumulated a very high volume of reports in previous years: TuExperto recorded over 120,000 in 2021, almost all related to commercial communications.
It is important to distinguish, in this case, between a commercial call historically attributed to an operator and a possible identity theft.
608881322: Aquaservice and commercial calls
The 608881322 does have fairly concrete references. TelefonoSpam collects a user complaint identifying the call with Aquaservice, or with a company that would work for it in customer acquisition campaigns.
Clever Dialer records 15 evaluations and 25 blocks in the last 30 days, with comments mentioning commercial calls from electricity companies, silent and persistent calls, and users who directly label it as spam.
The available information points to commercial activity, although user comments are not enough to automatically attribute each call to Aquaservice.
910623457: numerous complaints about alleged recoveries
The case of 910623457 is different and presents a considerable volume of negative reports. Clever Dialer collects ten evaluations that label it as spam or relate it to alleged calls from a lawyer for Orange.
On Tellows, there are 10 evaluations referencing Procobro, alleged recovery services and debt claims; some users say they have received calls or SMS demanding amounts they claim not to recognise. Another collaborative database adds 17 negative evaluations, under categories such as financial services, unwanted call, scam call, and debt collector.
These records are user testimonies and do not equate to an official resolution determining that the phone is used to commit a scam.
607100122: linked to Vodafone
The 607100122 also has a considerable history. Teledigo indicates that the number is marketed by Vodafone Spain and collects user testimonies that speak of calls offering improvements or service changes; one comment claims they could call several times on the same day. Another database identifies it with Vodafone Empresas and collects experiences of persistent commercial calls.
This allows it to be differentiated from other numbers on the list: there are references linking it to Vodafone, but just because a user finds its calls annoying does not mean it is a fraudulent number.
919199477: calls attributed to BBVA
The 919199477 is also associated with a well-known company. Some identification databases link it to BBVA Comercial and calls from bank sales agents.
Tellows collects five evaluations referencing a supposed BBVA agent, although experiences are not unanimous: some consider it a reliable call, while others label it as aggressive advertising or harassment. TelefonoSpam also collects a user comment who received a call claiming to be from BBVA, although there is no official confirmation from the bank regarding that number.
914444400: a case that does not fit the usual spam profile
The 914444400 is particularly striking because some sources identify it with ADT, the security systems company. Tellows collects five evaluations, all classified as reliable numbers, and several users point out that it is ADT's alarm central. Another specialised page also links it to ADT Smart Security.
However, there are directories that simultaneously associate it with commercial campaigns from Vodafone, Lowi, Jazztel, and other services. The discrepancy is precisely the reason why it is not advisable to automatically label a phone as fraudulent based solely on collaborative directories.
621194355 and 650773442: much search, little conclusive evidence
Other phones present a quite different picture. The 621194355 accumulates hundreds of inquiries in some directories: a specialised page recorded 728 searches, although at the time of the inquiry, the number had not been reported as spam.
The 650773442 appears as a mobile line associated with the Movistar block, but Tellows does not yet have enough evaluations to identify the purpose of its calls. In these cases, presenting the number as a scam would go beyond the available evidence.
What about the rest?
The public information on 917656887, 691850318, 787999777, and 4496890139 is much more limited than that of the previous phones.
This does not mean they are safe or that they are spam. It means there is not enough verifiable public data to reliably attribute them to a company or specific activity. The case of 4496890139 also requires some caution, as it has ten digits compared to the usual nine digits of Spanish phone numbers. It could be a copied number with some incorrect format, or a number from another country.
The underlying problem: knowing who is calling is not always enough
The concern over commercial calls has led Spanish authorities to introduce changes in the identification of these communications.
The Spanish Data Protection Agency generally requires prior consent for unsolicited commercial calls with human intervention, unless they can be justified by a legitimate interest under certain circumstances; moreover, the user must be informed of their right to object at the start of the call. Automated commercial calls, on the other hand, are not permitted without that prior consent.
The numbering is also changing: the CNMC promoted in 2026 a specific range starting with 400 for commercial calls, designed to make it easier to distinguish them from customer service calls. The initial assignment of this numbering was approved in July of that same year.
This is particularly relevant for numbers like those on this list, as some have the appearance of a conventional phone and do not allow one to know at first glance whether it is a commercial call, a legitimate communication, or something else.
What to do in case of a suspicious call
If the caller requests bank details, passwords, codes received via SMS, or sensitive personal information, it is advisable not to provide it during an unexpected call.
It is also not advisable to automatically return an unknown call. If the caller claims to represent a bank, a telephone company, an insurer, or another business, the safest option is to verify it through the official channels of that entity.
In the case of persistent commercial calls, the user can block the number and exercise their right to object. If they are registered in an advertising exclusion system and have not given specific consent to the company, the AEPD reminds that companies are obliged to respect that exclusion.
The 13 flagged numbers
The available evidence shows that these thirteen phones do not form a homogeneous group. Some have a history of commercial calls, others accumulate negative reports from users, and several appear linked, according to different directories, to known companies. There is barely any information on others.
More than a list of necessarily fraudulent numbers, what we have here is a set of phones that people search for and report, and on which it is advisable to check the context before returning the call or providing any personal data.
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