A recent comment on reddit by a user who seems to be a Purism employee sounds like phone call audio may be working now: https://www.reddit.com/r/Purism/comments/e8y36v/how_to_follow_librem_5_development_via_issues_at/fag2x8v
According to that comment, the following two actions may help:
It would be interesting if someone having a Birch phone could try this.
Someone (called âBenâ in Matrix librem community chat) confirmed that it works with his Birch device in that chat yesterday.
Another issue related to call has been fixed:
So they should issue a librem5 calls librem5 video and then concentrate on the power consumption.
@pit Well yes but actually no. Realistically we need both those things performing much better than they are right now when evergreen drops, or it wonât be a phone as we recognize it today.
Nah, thatâs just Echelon intercepting your call, copying it and then repeating it.
I just updated today on my Birch Phone. I am able to send audio (the microphone works), but I am unable to recieve audio. I installed linux-image-librem5.
I have also never gotten the speaker to work at all with audio. Alsamixer (the cli program) says I am at 100%.
You might want to head over into the librem5 community chat. Another user was able to make a call with audio with a little help from our friends in there.
Forgive my ignorence, where is that?
A Dev there says âthey need to adjust the Speaker alsa control, not the default pulseaudio one. a fix that provides some sane default value is somewhere in the pipeline already.â
Matrix chat is at https://matrix.to/#/#community-librem-5:talk.puri.sm
No need to apologize 
Thank you!
The command I needed was
$ amixer -c 1 sset âSpeakerâ 100%
I was able to make a phone call, and send/recieve audio!
Yay, thatâs progress!
good ! now start a new thread and link to it so we can all ride this horse untill it dies ! (of boredom) 
While it works, there is still a bit of work to do on it. Right now it seems that pulseaudio cannot control the volume of the speaker, so I had to manually tell it to turn up the volume (hence the command). From the chat, they have a workaround coming to have the speaker on, but you have to still manually change the volume. The microphone seems to work in pulseaudio.
What is really neat to see is they are upstreaming the fixes to pulseaudio, rather than going off on their own (which may fix the problem faster, but will cause a lot of headaches later).
The one thing that still needed tweaking got merged three days ago, so things should be much smoother from this point.