Was going to start typing an answer, but I'm working and don't feel like spending half an hour typing... so off to ChatGPT!
Carriers generally cannot detect when a caller is spoofing a phone number because of the way the current telecommunications system works. Here are the key reasons:
1.
Legacy Infrastructure- The telephone network was designed decades ago without strong authentication mechanisms. It operates on a trust-based system where carriers accept the Caller ID information provided by the originating network without verification.
2.
Lack of Authentication in Caller ID- Caller ID information is sent alongside the call setup data but isn't verified. The system doesn't check whether the number being displayed actually belongs to the caller, allowing bad actors to manipulate the information.
3.
Voice over IP (VoIP) Technology- Many spoofed calls originate from VoIP services, where users can configure their outbound Caller ID manually. VoIP systems allow this flexibility for legitimate purposes, such as businesses displaying their main number regardless of the specific extension making the call.
4.
International Calls- When calls cross international boundaries, the originating carrier's information may not be passed through the same way or verified by the receiving carrier. This creates an additional layer of complexity in identifying spoofed numbers.
5.
Lack of Universal Standards- Until recently, there was no universal framework to authenticate Caller ID information. However, the STIR/SHAKEN framework is being implemented in many countries (e.g., the U.S.) to combat spoofing by verifying the authenticity of Caller ID information. Despite this, it requires participation from all carriers in the call path, and implementation is still ongoing.
6.
Resource Constraints- Detecting and analyzing spoofing in real time would require significant computational and financial resources. Carriers often prioritize call routing and connectivity over such checks.
7.
Legitimate Use Cases for Spoofing- Some businesses and services legitimately spoof numbers, such as when displaying a toll-free number for customer support. Carriers would need to differentiate between legitimate and malicious spoofing, which is a challenging task.
8.
End-to-End Encryption- In some cases, VoIP calls may use encryption, preventing intermediate carriers from inspecting the contents of the call setup data to detect spoofing.
Current Efforts to Combat Spoofing
The implementation of frameworks like
STIR/SHAKEN aims to address these challenges by adding cryptographic signatures to Caller ID information, allowing carriers to verify whether the number is authentic. However, these measures are not foolproof and require global cooperation to be fully effective.
