Does mobile data work? That is, are you registering on the mobile network at all? (In order to be certain of this you may want to kill WiFi temporarily.)
Were calls working before the 3G shutdown?
Otherwise, as Frankly says, you do have to enable VoLTE explicitly. It is disabled by default.
I’m with Belong too. I can confirm that after enabling VoLTE, I have absolutely no issues with phone calls, SMS, MMS, etc where I am. That said, I’ve had Belong email me saying that my phone doesn’t support 4G, and that they’ll deactivate my service on the 28th of November. Have you had any similar emails, or is that just me?
When I have time to sit on hold for an hour+, I intend to call them from the Librem 5, prove that my device does in fact support 4G, and get them to stop trying to stuff me over.
Sorry I should have mentioned that Belong is owned by Telstra and the inexpensive part of its network.
Thank you for the pointers to sort the issues. I did email Purism support on this 3G issue before I thought to look on this forum first. I hope to get a reply in a couple of days and maybe an explicit guide to the bm818-tools to do the fix.
Cheers
Short answer is NO mobile data doesn’t work either. Sloppy late night thinking that if mobile is updating OS then mobile data is working. 
Yes calls were working before 3G shutdown.
Will be going the enable VoLTE explicitly route in due course.
Yes I did get an email from Belong - here is a quote:-
" The Telstra 3G network closure is just one month away.
As you know, you need to upgrade your phone before then (Shi BroadMobi BM818 - mobileno).
But because everyone loves a perk:
If you upgrade to a compatible phone before Sunday 6 October 24, we’ll add three months’ credit to your account. Nice."
Needless to say I didn’t take up the offer…
Not a good sign. Can you tell whether you are registering on the mobile network correctly?
How to enable VoLTE: No Dial when making call on Librem 5 - #12 by irvinewade
Obviously you will need to be on WiFi to do that.
As of this morning my L5 on Telstra is no longer able to send or receive calls. Yesterday it was fine with calls but started to become patchy with text messages. It gave me some grief last week but came good and was working perfectly for all functions on Thurs/Fri/Mon this week. Then a decline in reliability up to today with no call capability. I have no idea why as I haven’t done anything to the phone as I’m not a tinkerer once I get it right. Its a battle that I suspect is not of the phone’s making but rather the telcos.
I suspect that they have blocked it as it’s not an approved device for VoLTE. That’s my issue here in Canada.
I suspect you may be right. The obvious two questions would be 1. Is the phone able to register on the mobile network? 2. Are you getting mobile data? If “no” to the first question then I think you need to ring Telstra and ask them whether they have blacklisted your phone.
FYI, the issue here in Australia is not whether it’s an approved device for VoLTE but whether it is successfully able to call emergency services via VoLTE. This of course is not something that any user can readily test. (In other words, VoLTE may be working fine and the telco knows it and the telco is happy with the use of VoLTE on that phone but if the phone can’t call emergency services via VoLTE then by law the entire service must be blocked.)
Edit: PS This is something that the government announced just a few days ago. So there is a lot of confusion between
The phone is getting the “4G” in the top line. I appear to be able to receive texts but sending them they don’t always get to their destination. I can’t be sure that I’d be getting all incoming texts as I can only test from a couple of phones. I can ring Telstra of course but I get a trauma response just thinking about it.
Because I need reliability I have a google pixel 7a with Graphene arriving tomorrow from overseas which is guaranteed to work (we’ll see). I’ll begin to use this one because I need the phone to work. I’ll still play with the L5 on the Vodafone or Optus network and see if things come good.
You and me both, mate. 
You can’t meaningfully test on the Optus network yet because Optus is phasing out 3G over some months unless you are certain that 3G is already gone in your area on the Optus network. The same applies on the Vodafone network if your plan involves sometime use of the Optus nework i.e. roaming to Optus in areas where the Vodafone network is too sparse.
Edit:
I suggest checking with Settings / Mobile / Modem Details where you should see Carrier, Network Type, Network Status.
I’m not in a position to know for sure what these look like when you are blacklisted but I think that you have not been blacklisted and that your problems lie elsewhere, although those problems may well relate to the 3G shutdown.
Shows Telstra network type is ‘lte’ and registered on the network. It looks ok.
For continuity. I have changed to a Vodafone card today and things seem to be working without a drama. I can make/receive calls now, send/receive texts etc. I have “4G” in the top bar but with an orange “!” in the signal strength bars. But this exclamation mark seems to come and go over the course of the day. Does anyone have any idea what that means?
So I will now persevere with Vodafone and see how it goes. From the time that 3G was supposedly turned off Vodafone has continued to work. There was window of almost a week of Telstra working but that appears to have stopped. Fingers crossed for Vodafone now.
I believe that it indicates that mobile data is “off”. That could happen if you are on a plan that allows roaming from Vodafone’s network to another network, and that roaming is happening e.g. if your signal is marginal on Vodafone’s network. Or it could just be a bug. If you go to Settings / Mobile and turn Mobile Data “off” and then turn it back “on” again, that will often clear the problem.
Regardless of whether mobile data is “on” or “off”, that need not interfere with other actual mobile network functions (such as making and receiving calls).
Thanks for that, It was indeed off. It seems to have a mind of its however as it comes and goes. Maybe as I move around?
For me it usually sorts itself out by itself eventually but if I can’t be bothered waiting, I use the workaround noted (turn setting off and then on again). In my case I am definitely experiencing roaming because Settings / Mobile / Details shows a change of APN.
I have now had one week using Vodafone on the L5 and it seems to be fine. I suppose that the only issue is whether the complete turn off of 3G has occurred and what I am experiencing is how it will be from now on. But no problems so far.
Update here as a Belong (Telstra) user. The phone works for everything except calls. Calls don’t ring whether I try calling someone, or they call me. Belong is still threatening to cut off my service in a couple weeks. My understanding is that Telstra has some weird VoLTE configuration requirements compared to other providers and so the phone doesn’t work on their network. If anyone is with Telstra and can still make/receive calls, I would appreciate any insight as to how, because I really don’t want to toss the phone when it still works perfectly.
Unfortunately, swapping providers is not an option for me. Telstra is the only provider that has reception in my area.
Residents of Australia and travelers to Australia should read this: Australia’s 3G Shutdown - Why your 4G/5G Phone is now Blocked!
@JCS, I hope Purism is fully aware of the implications.
@irvinewade, the article also sheds light on this: