HI,In the last the code 2300 and 128 have been popping up on my usage as text messages. Please provide information as to what these codes are? The 2300 is 8-10 in a row at times.

Hey all! We love that you are taking advantage of the app and website to keep an eye on your bill and usage details. It can be nerve wracking when something new shows up that doesn't totally match up with what’s on your device. It took me a bit of time, but I was able to clarify with some of our messaging and billing teams that the 2300 code is used for Multimedia Messaging routing (think picture and group messages) and 128 is used by our voicemail system. These codes are used on the system side of things to deliver and confirm delivery of your important data, so it shows on the bill as a stamp. The phone does not show the short code because it receives the real important stuff; your messages and voicemails.

Text code 128 and 2300 | T-Mobile Community