A growing number of online services is turning to mobile phone numbers as the means of authenticating their users and buyers. For instance, some mobile applications or web services will download or activate only after the user has entered the one-time PIN (usually a four-digit number) delivered to their mobile phones via SMS.
This flow requires users to provide a valid mobile number at some point in the process, which leaves room for mistakes. Some users might provide landline numbers, to which OTP cannot be delivered over SMS. Sometimes they can make inadvertent mistakes – type in an incomplete or invalid number. Users may misunderstand instructions and provide a VoIP number, also not a good basis for validation of this kind.
According to some sources, 4-8 percent of numbers provided for SMS-based authentication are invalid, expired, VoIP or incorrect numbers. This makes it harder for online companies to perform user authentication, because their systems are attempting to deliver one-time PINs to non-existing numbers which can’t receive them. In some cases this will obstruct the entire app installation or service registration process, with potentially negative impact on conversion rates and/or sales.
However, there is a telecoms-based solution to this problem. Usually described as number validation, it relies on home location register, a central database that contains details of mobile phone numbers, and is authorized to use the GSM core network data.
This technology provides an automatic (and completely anonymous) check of any GSM mobile number’s validity - whether it's inexistent, unused or a landline, and without revealing any information on the mobile subscriber.
Easy to integrate over API, this kind of telecommunications technology allows online services and mobile app developers to determine with great precision which of the provided numbers are valid mobile phone numbers.
That way, online services can make sure that their SMS messages with one-time passwords are only sent out to those numbers, which helps optimize costs, but also reinforce security efforts.
Secondly – and more importantly - the information can be decisive for a successful conversion, i.e. an actual purchase, download or app activation. Number validation enables online services to alert users to re-enter a correct mobile phone number, so that the process can be successfully completed - and user drop-off rate decreased.
Number validation is completely invisible to users, running in real time in the background, and adding no hassle to the overall user experience. It is becoming a necessary element in many kinds of online authentication flows – for mobile apps, social networks, e-commerce sites, booking sites etc.
With it, any service provider can delete invalid numbers from their database, making sure that it only contains valid ones.