Yes, you are able to download and register for a GCash account if you have an active Philippines mobile number (any PH network), even while abroad. If you are currently overseas, do make sure your SIM / mobile phone has activated Roaming.*
To enjoy access to all of GCash’s marketplace of products and services, verify your GCash account. Do note that only Filipino nationals are accepted and that you need to use your Philippine address when you register and get verified.
GCash has partnered with global remittance partners for you to cash in to your own GCash wallet or to send remittances directly to your loved ones in the Philippines.
For more information on how to add funds to your GCash wallet, visit How do I cash in to GCash while overseas?