Spain has good mobile coverage, so it is easy to stay in touch via phone. Don’t forget to make sure your phone will work overseas. If in any doubt, check with your provider.

You can either use the phone via roaming on your current network (you will need to activate roaming on your phone at least a week before you go or via a prepaid Global SIM card or via a Spanish SIM card to save on costs. The most cost-effective option will depend on whether you make a lot of local calls (local SIM is probably better) or international calls (Global SIM or roaming will probably be cheaper). 

WiFi is readily available most of the way along the Camino, from bars, restaurants and albergues. Keeping in touch via email, or Skype or WhatsApp may be cheaper than texting or calling.