Number Lookup FAQ

[Charlene_Kwong]

1.      Does Number Lookup V2 work in the same way as legacy Sinch Number Lookup services?

No. Older Number Lookup services typically use Home Location Register (HLR) Lookup as the data source.  Sinch’s first release of Number Lookup is based on data derived from National Regulators.  This means that the results and how those results have been derived cannot be exploited by use-cases in the same way.

2.    What is the difference between this service and HLR Lookup?

HLR Lookup is usually a live-lookup into a Mobile Operators subscriber database.  However, some suppliers of this service use a cached lookup to save money.  A valid response to a Telephone Number request from a HLR Lookup usually means a Telephone Number is active on the mobile operators network.  The problem with this approach is that it exposes the mobile operator to personal data-loss, since operators never intended to provide access to such information.  It is quite difficult for operators to removed access to such a service, but they have found ways to limit access as well as obfuscate any information provided. 

This has led to significant changes in availability and accuracy of information from HLR Lookup.  For instance, a HLR Lookup, if available, will typically only provide intelligence that a Number does belong to that operator, but cannot be relied upon to be live in the network or located in particular part of the global cellular network.

Sinch Number Lookup provides a more consistent set of results since it is based on regulator data.  When a response is returned, it returns information about how the national regulator has assigned a number to an operator.  This does not mean it is active, but that the number is available for use by an operator.

3.    Will this service meet my needs?

HLR Lookup may have previously supported multiple use-cases:

• Message routing, with Port-correction
  • Special permission is now required by Mobile Network Operators (MNOs) to perform this function.  This use-case is no longer supported.  However, in North America, Sinch Number Lookup is port corrected and can be used for routing.  Sinch may add port-corrected results globally in the future.

• List Cleaning for “active numbers”
  • HLR Lookup may have supported this use-case several years ago, but changes in the mobile operator have reduced the efficacy for such a use-case.  This is no longer supported.  However, Sinch Number Lookup will help you understand if a number is properly formatted and of a line-type you might expect for a customer engagement.  It is important to remember that any customer list you have must comply with Data Protection laws and if it does, then the relevance of an ‘active number’ service is diminished.

• Subscriber Location
  • HLR Lookup would previously return the network address, country location and roaming country of a mobile subscriber.  Since 2018, this is no longer the case, since location is a sensitive subscriber attribute.  All operators have made significant efforts to block access to this information.

4.   Will all the missing features in the legacy API be replaced?

No. Sinch is building a Number Lookup product and roadmap that aligns robustly with global data protection regulations.  However, Mobile Operators are releasing new capabilities that such new data items (such as location), but doing so with a consent mechanism built in.  Sinch will be introducing these services as and when they become available from mobile operators.

5.   The data for non-US/CA are not port corrected. What are the values of these data?

1. Cost efficiency: Non-port corrected data is significantly cheaper than real-time HLR lookups because it doesn’t require access to live network feeds. 
2. Performance and Scalability: Without the need for real-time lookup, non-port corrected data offers faster lookup times, making it highly scalable for bulk operations. 
3. Workflow optimization: If the a number is ported, the line type will remain the same. Enterprise can categories the numbers based on line type attributes for campaign targeting and fraud mitigations.
4. Routing value: For customer requires live routing, non-ported corrected data is not designed for it, it can still meet basic routing needs.

6.   What is the rate limit for the API?

To enhance our service efficiency, we have implemented a rate-limiting mechanism for the Number Lookup API.

The Number Lookup API offers three tiers to cater to different customer needs. If premium or custom tier is required, please contact us to enable it.

Tier	Requests per second
Basic Tier (default)	10
Premium Tier	100, available upon request via our support team
Custom Tier	For enterprise customers with specific requirements, the rate limit can be customized based on your application configuration. Please contact our support team to discuss your needs and configure the rate limit accordingly.