Carl Hutzler’s Blog

The other day I was using my Sprint cell phone as a modem connected to my laptop over bluetooth. I was surprised to receive a normal voice call during the data connection. I took the call as normal and when I was finished I hung up and the data connection went right back to working without having to do anything on the laptop. It was just like my old Cingular service used to work. Why was I surprised? Well because I have always been told that this capability (to put a data session on hold and allow a voice call through) was an amazing feature of the GSM cellular technology and the antiquated CDMA technology just “could not do this”. Those darn sales people.

So I looked online and found out that Sprint does allow incoming calls to your phone during a data session BUT only if the data TX and RX happen to be idle at the moment the call comes in. I guess I was just lucky the other day when the call came in as my data session must have been fairly idle. So I poked around a little more online and found this site which explained how to switch the feature to ALWAYS allow a voice call to place your data session on hold. And I just tried it and it works exactly as you would expect….you are in a data session using your phone as a modem and a call comes in. The data session is “put on hold” while you take the call. Then when you hang up the voice call, the data session resumes automagically. Laptop has no idea the data session even paused! (of course if you are on the phone for a long time, I imagine some data session stuff might time out on the laptop, but that’s another issue)

Anyway, the way you do this is right on the web page above. It involves going into the service menu on your Motorola V3m phone (by entering ##3282# as the phone number). Then you select EVDO from the menu and edit the DDTM setting to be OFF. Very simple, but you need to get your phone’s MSL code to do it!! This code, called the Master Subsidy Lock, is of course some silly secret of the cell phone company. And they usually will not give it to you. But I found a simple way to make them give it to you. Just call up and say you put a security lock code on your phone and have forgotten the password lock code. They will tell you to try the last 4 of your SS# and the last four of your phone number, and a bunch of other stuff. Just say “its not working”. Then you will get transfered to technical support. They will tell you to enter the magical service menu by hitting ##3282# on your phone. Once in, they will walk you through the menus and eventually tell you to hit EDIT on one of them to reset your lock/security code. The phone will then ask for your MSL code before letting you do this. Just write down what the tech support guy tells you. Now you have your MSL !! (fyi, the MSL is different for every phone and its based on the IMEI code which is unique to every device…so don’t use an MSL code for one phone on another phone even it’s the same make/model or you can lock your phone forever as this code is also related to unlocking your phone so you can use it on other cell networks).

Dial *2 for Sprint customer service :-)