A dear friend of mine in the U.S. recently told me that she had been quite hurt by the unkind texts I had sent her after the Holidays.
I do not have a texting mobile phone, nor do I do texting from my landline at home. She claims it came from my number and under my name to her mobile phone in the States. I have lived in Europe for 3 years with no texting ability from here. How can this happen?
To answer the question given in the title:
How can someone spoof texts with my phone number?
First, it is important to understand that one of the central systems phone providers use to communicate and to send information from one carrier to another (SS7) is based on trust. The system was developed in a time when all operators would trust the information received from others.
This gives way to sending information into a network with false content, something that is very easy, given that you have access to a SS7 gateway into the network. A carrier can simply tell another that the message is from a specific number, and this will be accepted.
More practically for the average Joe is to use internet services that give you the option to enter the desired sender's number, such as this. You are then able to send SMS messages pretending to be someone else.
Further to Hans' answer, some handsets allow you to use it as a modem and send a binary SMS via the AT command set; header fields in the message can set the number displayed. There's a lot of variables depending on the handsets and networks involved, but it can sometimes easily be done without needing a gateway service - I experimented with this for a prototype voicemail-to-mms service.
I can't recall or readily find the specifics, but for the gory details, try searching for binary sms at command on your favourite search engine.
