Pi-Star

Pi-Star is a prebuilt Debian image for Raspberry Pi that includes Multi-Mode Digital Voice Modem (MMDVM), DMRGateway, and a web UI. It provides an easy way for users to construct a DIY hotspot using MMDVM, which supports DMR, D-Star, Yaesu System Fusion (YSF), M17, P25, POCSAG, and FM.

A static IPv4 address is not necessary for hotspot usage, but can be convenient for remote management so that dynamic DNS is not necessary. 44Net Connect usage is not officially endorsed by Pi-Star, and requires manual iptables management.

What you need

A 44Net Portal account
A verified amateur radio callsign
A Raspberry Pi running Pi-Star (downloads and install guide here)
Some sort of internet access
Some sort of digital voice modem hardware (unless you intend to operate an internet-only reflector)
DMR users need a DMR ID from RadioID.net
NXDN users need an NXDN ID from RadioID.net
Users setting up a DMR or NXDN repeater need a Repeater ID from RadioID.net

If you haven't set up your Portal account or verified your callsign yet, see 44Net: Get Started for instructions.