If you are managing IP addresses with phpIPAM, you can easily migrate your IP inventory into Device42 using the script linked below. This script connects to the phpIPAM server (v1.2.1 and above), and extracts the data, sending it to Device42 via the REST-based APIs.
This python script can be run from either Windows or Linux machines with Python 2.7.x. Requires netaddr, pymysql, and requests. Full details can be found on the GitHub page & in the README.md file.