The question, on the surface, seems pretty straightforward, right? The phone number is either valid or invalid, and there should be tons of services providing that information. However, that’s not always the case.
The typical definition of phone validity is:
- Confirm whether the local phone number syntax is valid.
- Confirm if the numbers are even assigned to a carrier within a specific country. For example, a number is considered valid in the U.S. if it is part of the North American Numbering Plan.
If these two criteria are met, the number is considered valid, which is a fair and standard industry definition. Beyond that, a validation service typically also formats the number in local/international format, provides country code/name, etc. A few services also include the carrier and line type information of the phone (e.g., whether the phone is a mobile or landline and what carrier it belongs to).
This, of course, is valuable, but it also misses out on a few things.
Yes, the number might be assigned to a carrier, but it very well might not be assigned to a subscriber. Meaning, if you call this number, you will get a disconnected tone. Is the number being valid still of much use if you get a disconnected tone? This is why it’s important to have a phone validation service that not only determines whether the number is valid but also whether the number is connected. So, if you call or message someone, you know they will receive it on the other end.
Similarly, depending on the use case, businesses might want to know the line type detail in more fidelity than just mobile or landline (e.g., is the number a virtual number, like Google Voice or Skype?). These numbers are easy to get online, but you do not receive any physical address associated with it, and it does not help with any kind of message deliverability. In fact, they are used most often for promo abuse and fraudulent sign-ups. The carriers providing these services are mostly Mobile Virtual Network Operator (MVNO) carriers. The phone validation service should be able to identify these carriers and line types as non-fixed VoIPs. This allows businesses to filter out these numbers before sending a message, deprioritizing leads with these numbers, and flagging any sign-ups for potential fraud, which adds additional friction.
Trestle’s Phone Validation API provides these additional attributes and fidelity for businesses to make the right phone validity decisions. Trestle’s Phone Activity Score determines the activity associated with the phone, and anything below a score of 30 is generally a disconnected phone. Similarly, the line type returned includes non-fixed VoIPs by identifying these MVNO carriers. In addition, it also provides a prepaid flag that might be of value to certain customers.
Businesses, depending on their needs, should choose the right service and add the necessary level of checks as part of phone validation. For example: Businesses looking to buy/generate valid leads should not just check for whether the phone is valid or not but also whether the phone is connected or disconnected. Similarly, a business looking to avoid fraudulent sign-ups should confirm the phone validity, as well as whether the line type is not a non-fixed VoIP.
Rule sets to use with Trestle’s Phone Validation API for various use cases for ‘true’ phone validation:
is_valid = true && activity_score > 30
Fake Sign-Ups/Promo Abuse:
is_valid = true && line_type != “NonFixedVOIP”
is_valid = true && activity_score > 30 && line_type == “Mobile”