>>3

>スナドラ660内蔵モデムはx12lteという型番でdsdvには対応していません。

んなことないだろ

Cellular Modem
Modem Name: Qualcomm® Snapdragon™ X12 LTE modem
Multi SIM: LTE Dual SIM　　＜ここ
Next-generation Calling Services: VoLTE with SRVCC to 3G and 2G, Voice over Wi-Fi (VoWiFi) with LTE call continuity, HD and Ultra HD Voice (EVS)