Shutting down 2G will have a significant effect on the way the Verizon's network works for voice calls. That's because Verizon's 3G EVDO technology is data-only. Without 2G, the only way to make calls will be with Voice over LTE (VoLTE).
Only Verizon's newest phones support VoLTE so I have my doubts that Verizon will be able to update or replace every single user's non-VoLTE phone in less than three and one half years. Hamby optimistically noted that customers upgrade their phones every 2.5 years on the average. But Verizon's Prepaid and MVNO users present a particular problem. Prepaid users tend to use older, lower-end phones and replace them less often than post paid customers. TracFone, Verizon'd largest MVNO, has millions of customers with 2G feature phones, especially on its TracFone and Safelink brands. Many of the entry level or older smartphones used on Verizon Prepaid and Verizon MVNOs do not support LTE and almost all of them do not support VoLTE.
In order to shut down 2G by the end of 2019 without losing lots of customers, Verizon needs to replace ever single non-LTE phone with an VoLTE capable LTE one. It also needs to either replace or push a software upgrade that enables VoLTE to every non-VoLTE LTE phone. TracFone has to do the same for the millions of Verizon network customers on its TracFone, NET10, Straight Talk, Page Plus, Total Wireless and Safelink brands. Smaller Verizon MVNOs like Selectel, RedPocket and Envie probably don't have the resources to replace customer phones for free and will probably tell their customers to buy a new phone or switch to a different network or carrier.
Although this change will be disruptive for many prepaid customers, the switch to LTE and VoLTE should also bring some benefits. LTE data is much faster than 2G or 3G data. VoLTE will provide better voice quality and will also allow simultaneous voice and data use, which is not available with most recent Verizon LTE phones. The switch to VoLTE should also mean the end to some Verizon MVNOs policy of not allowing LTE phones on their lower priced plans.
Source: Fierce Wireless