How to report a phishing text?
In the USA, you can report SMS phishing attempts to the US-CERT by forwarding them to 772-6; emailed phishing attempts can be reported to phishin[email protected]. See the US-CERT website for more details.
In other countries, you'll have to check with your own government.
While there's already an accepted answer, it's local to the United States. This answer hopes to contribute similar information for Canadian readers.
I was recently targeted by such a text (in Canada). Here, we have the GC spam reporting centre, a government-run branch for spam reports.
If the phishing attempt includes a website, you may be able to find the registrar via a WHOIS query, and hit up their abuse centre (usually listed on their homepage). In my case, the registrar had suspended the domain within 24 hours of my report.