I did a Google search for PLS8 and BM818 and “certification” or “certified” or “whitelist” or T-Mobile or AT&T or Sprint or Verizon, and I can’t find any mention of these two modem models being certified for any cellular networks. BM818 doesn’t publish much public info about its modems, but it also seems to be mainly focused on the Chinese market, so I think it unlikely to be certified for any carrier. There should be some mention in the Gemalto forum if the PLS8 has been certified for a carrier.
I based the wiki text on this comment by Nicole Faerber in August 2019:
we (as in Purism) currently have no plans to get additional carrier approvals. Getting carrier approvals is a PITA and in most cases bound to very high restrictions on the device and a very expensive qualification process. Especially the restrictions carriers in many cases impose on handsets and their features or access of the carrier onto the handset (for remote configuration etc.) are “features” we do not want to have on our device. We want the users to have the maximum freedom on their device and not being forced to have locked down parts.
So if Sprint is not supporting our modem, I am sorry, the Sprint is not an option. In the US I know that e.g. T-Mobile is very open, in Europe it is the law that carriers must accept all 3GPP compliant devices.
That was a long time ago, and maybe Purism’s plans have changed since then, in light of the announced blocking of non-VoLTE phones by T-Mobile and AT&T, and the fact that the one person who has tried to use Verizon with the Librem 5 had problems.
If Purism is going to provide the AweSIM service on the T-Mobile and AT&T networks, it has to be in conversations with those two carriers, so I think it likely that Purism will have to work something out with them if they decide to restrict access to only whitelisted phones in the future.
Reading between the lines from what @dos posted (see the wiki for links), it sounds like BroadMobi can update the firmware to support VoLTE, and I imagine that is what Purism is waiting for, but it also sounds like BroadMobi isn’t the most responsive company.