I have found that DTMF doesn’t work reliably with PJSIP. One of my first installs of FPBX Distro about two years ago I didn’t know better and had all the extensions setup as PJSIP. Many of the users complained about the menus of other systems they were calling not always recognising their key presses and after switching them to cha_sip the problems went away.
I am slowly “experimenting” with PJSIP again with the odd extension here and there over several client installs (particularly those that need to be able to be logged in to more than one device simultaneously), and so far no complaints fingers crossed