Can I determine the actual sender of a spoofed text message? I received a text message yesterday that appeared to come from one of my contacts, but he did not send it. I contacted my carrier (Verizon) and they said that because the sender used third party software, they couldn't tell me where it originated. But they did say that the sender had to enter both of our numbers into the software, so we were targeted specifically. We have a rental business and have been threatened recently over evictions we're doing. I'm concerned for security reasons.
Your carrier is definitely able to tell who sent the text, as the sender's carrier's servers obviously connected to your carrier's ones to deliver the message and everything was logged.
They just don't want to go through the effort of diving into log files which would require paying for engineer time because the people who work at their customer service are only trained to sell stuff and don't even know what is a "spoofed SMS" (the incorrect explanation they told you proves it, no matter what software sent the message they should still have a log of where the message came from, whether it's their network or some other carrier).
Your friend should take legal action for identity theft, then the police will force your carrier to disclose any info they have about that SMS, including the origin carrier, from there they contact that carrier and they should be able to give them the identity of the person who sent the text (or at least, some possibly anonymous IP if it's an SMS API provider, but it's still worth a try).
The caller ID or SMS sender is just a string field without any particular meaning, while you can't spoof that using your mobile plan because your carrier always puts your number in that field on their side, you can definitely spoof it if you are a carrier yourself and have direct connections to other carriers, in which case you can pretty much put anything in there and your call/SMS will be delivered just fine with that (spoofed) caller ID/sender. Most SMS APIs offer that as a service so companies can send marketing messages originating from "company name" instead of a phone number, but of course the actual sender is logged on their servers for obvious purposes.