When moving between different countries rather than roaming on their home plans, customers may want to use a local SIM card to access local, cheaper data and calling options.
Like all Nexus phones, Nexus 5 is not locked to a wireless carrier. Swapping service between networks is easy.
When using the North American variant (D820) you can use the device to connect to any GSM network, or with a Sprint SIM, you can connect to Sprint's network (CDMA and LTE modes).
Swapping SIMs between GSM-based carriers requires no special settings or processes.
However, when they switch back to their previously-activated Sprint SIM, they will need to update certain settings to continue to get service successfully. This process is outlined below.
Starting with a phone activated on Sprint, you can put your [Carrier] SIM in without an issue. The device will ask you to reboot and you will then have access (assuming that the SIM card is provisioned with an active account and service).
Starting with a phone activated on a GSM network, to switch to Sprint you’ll need to insert an activated SIM card, reboot, update the PRL first, then the Profile and then reboot. Click here for help with Sprint Activation.
To update the PRL, from the Home screen tap Apps > Settings > More... > Mobile networks > Carrier settings.
Tap Update PRL. When the PRL has been upgraded, tap OK to continue.
Tap Update Profile. When the Profile has been updated, tap OK.
Reboot your device. Once rebooted make a call to ensure it is activated.
Note: Once you've done that you can get to the network without a problem. You need to repeat if you switch to GSM and then back to Sprint again.