WhatsApp for Samsung Galaxy S5 CDMA

Verizon, Sprint and other US carriers have retired their CDMA networks, and the S5 CDMA lacks VoLTE on most of them, so calls and SMS stop working even when you see signal bars. There is no on-phone setting that fixes this. As a workaround, use data/Wi-Fi apps like Google Voice or WhatsApp for calls and texts, and ask your carrier about a free VoLTE-capable replacement device. Open Settings > About phone to confirm your exact model, since only some S5 variants ever got VoLTE provisioning. See how others solved this on Reddit

CDMA phones are activated by their MEID/ESN rather than by swapping a SIM, so the carrier has to whitelist the phone's serial number before it will connect. Find the MEID under Settings > About phone > Status, then give it to the prepaid carrier and ask them to provision the device on their CDMA list. If they can't add it, the phone is likely still locked to the original carrier and needs unlocking first, or you'll have to move to a GSM/LTE plan instead. See how others solved this on Reddit

CDMA-only S5 variants won't connect to most overseas networks, which run on GSM/LTE, so abroad the phone often works only over Wi-Fi. Check whether your unit physically has a SIM slot (most S5 models do), and if so, ask your carrier to unlock it and insert a local prepaid SIM. If it's CDMA-only with no usable SIM, rely on Wi-Fi with Google Voice or WhatsApp, or rent a local handset. See how others solved this on Reddit

Airplane mode should cut all cellular radios, so if messages still arrive you most likely have Wi-Fi or Wi-Fi Calling still enabled, which routes calls over the internet. Swipe down the notification panel and toggle off Wi-Fi (and Wi-Fi Calling if your carrier app shows it) in addition to Airplane mode, or simply remove the SIM. To stay fully unreachable, also switch off mobile data via the quick-settings toggle or under Settings > Connections > Data usage. See how others solved this on Reddit

The S5 stopped getting security updates years ago, so avoid banking and other sensitive logins on it, but it still handles media, calls and light apps if you keep it lean. Disable bloatware and clear space under Settings > Application manager, use a lightweight browser, and only run updated apps that still install from the Play Store. Swapping in a fresh removable battery is the single biggest thing that makes it feel usable again. See how others solved this on Reddit

Many owners keep the S5 going long past its update window thanks to its removable battery and microSD slot, but the dead CDMA network and missing security patches are the real limits. If your carrier still supports it, drop in a fresh battery and a larger microSD card and it remains a fine backup phone. Once calls and texts stop working on your network, it's time to move to a VoLTE-capable device. See how others solved this on Reddit