2 Modems (1 for Voice / 1 for Internet)

I have a Netgear CM2050V that works great for our Xfinity Voice service, but is not capable of the "Next Gen Speed Tier" (mid-split) faster upload speeds. I could purchase a Hitron CODA56 modem (that is capable of the Next Gen Speed Tier" upload speeds), but does not have a telephone port for our Voice service. There is already a splitter on the coaxial line before the modem to reduce power levels. Would it be possible to arrange with Xfinity to have the splitter connect to 2 different modems and designate the CM2050V to connect just to our telephone for Voice service and the Hitron CODA56 connect to the router for Internet service? Not sure if this is allowed. Thanks.