French Mobile Provider Freemobile and Volte

[Heryan]

After several tests, I must admit I misunderstood the observed behavior. Indeed, I don’t think suspend mode is the issue. As Laurent wrote, it seems Free Mobile doesn’t allow VoLTE for the Librem 5 modem (even the T1 version). I naively thought that when VoLTE was enabled and the LTE call verification (the “Check call for VoLTE” button on the mb818 tool) displayed FDD LTE (even before making a call), it meant the operator’s network supported VoLTE. However, the same verification, after my calls went through, shows “UMTS” or sometimes “HSPA+”. So, no VoLTE!
I therefore agree with some of the comments discussed in the following thread regarding the acceptance of VoLTE-compatible phones by certain operators:

Why is the Librem 5 blocked from nearly all phone companies?

I recently tried to re-establish phone service with Boost Cellular and learned that the Librem 5 is not authorized to use their system. This was a surprise because I used Boost Mobile in the past with no problems. Are there any cheap alternatives $25-$35 range that allow the Librem 5 to run on their systems? Now I have a Librem 5 phone but, unless I want to pay more for the Purism endorsed carrier, I cannot use it.