What is the problem? Please be detailed.
Using ODK1 I could get the IMEI of the device using the deviceID type in the survey sheet. This worked great. I am moving over to ODK2 to take advantage of the greater capabilities, however I can't find an equivalent tag for XLSX Converter. I can find reference to opendatakit objects available, but no list of what they are (I'm assuming this is where I would find the function I'm looking for?). I'm guessing something along the lines of opendatakit.getdeviceID()?
What ODK tool and version are you using? And on what device and operating system version?
ODK 2, Version 2.1.1 on an Ubuntu 18.04 Server and Android devices