[bevenky]

In general most APIs incorporate number portability for US. It's much more harder to do this for countries internationally.

We at Plivo also provide such an API which incorporates number portability for US: https://www.plivo.com/docs/lookup/

Plivo's API above is updated on a daily basis for portability information.

Caller ID as you mention for voice calls is quite easy to spoof, however with the STIR SHAKEN rollout, the intention is to make carriers accountable. SMS however with 10DLC is almost impossible to spoof the number.

[cvalka]

What about number portability in other countries? Why don't you let your clients port out their non US numbers?

[troydavis]

This discussion and the parent comment isn’t about whether they allow porting numbers. It’s about whether a number information API (CNAM) - where you’re querying for information about a number you don’t own - includes the carrier that a number has been ported to.