Anonymous Cell Phone User writes "Earlier today, I called a friend on my cell phone and was connected to "Tom", a stranger. I knew I didn't have the wrong number because my friend's number was saved in my phone. I tried the same number again and got my friend this time. My friend told me he had just gotten a call from somebody wanting to speak to Tom, but his caller ID had said that the call was from me. This has happened to me a few times, both when I tried calling somebody on a landline from my cell phone and also when somebody tried to call me on my cell phone from a landline (it might also have happened between two cell phones once, but I'm not sure about that). The information in the caller ID seems to always match the intended call, but the voices get switched. I have had this happen with a Cingular/ATT contract in the USA and with a Vodaphone pay-as-you-go card in Germany (different phones). I am wondering if this error is due to a limitation of the GSM protocol or how it's implemented. I'm hoping that there's some cell phone / telecommunications expert here that can shed some light on the issue. Can anybody here explain how/why these errors happen?"