One must be careful and retain a healthy dose of scepticism when it comes to answers posted online. I was gullible and wanted to believe the answers posted here, but I decided to double check and went into a store to look at the box itself, and worst case, there might be someone on site who could answer my questions in person!
What I have found out is there are at least 2 variety of this line of "modem" from Motorola, one of which DOES in fact support telephony, but has no wi-fi capabilities. So you would need to add your own wi-fi router. This version of the modem has two RJ-11 (for regular telephone jack connectors) ports in addition to the four RJ-45 (for Ethernet cables) connectors. The picture of the back of the advertised "N450 N Router With 8 X 4 DOCSIS 3.0 Cable Modem" shows that it has only the four RJ-45 ports, and no RJ-11 ports, therefore, it definitely DOES NOT support telephony.
There are indeed two modem/router combo at the store that supports both telephony and wi-fi, one is an ARRIS brand, and the other is NETGEAR. I strongly advise anyone who is planning to purchase this modem to visit the store, and at least speak to one of the sales representative before making the purchase.