Create an account, add the phone number that should ring, and send email to the address you are given. That is the whole setup; the rest is deciding which emails deserve a call.
1. Create an account and add a phone. Sign up and Email2Phone assigns you an address in the form yourname@email2phone.net. Add the number that should ring: a mobile, a landline, a desk phone or a VoIP line. There is no app to install. One setting on the phone matters, and it is the one people skip: switch voicemail off on any number that takes alerts somebody has to act on.
2. Send email to the address. Point something directly at it: a monitoring tool’s notification contact, a NAS, a UPS card, a sensor gateway, a mail rule in Gmail or Microsoft 365, or a person typing it. A connected mailbox is different: it is fetched live when you dial in, and it never rings the phone.
3. Send a test. Your phone rings and announces one message. Press 1 to hear it, then 8 to save it, which also acknowledges it (5 or 7 would too). From then on, everything that arrives at the address rings your default number until you add filters to narrow that down.
The free trial covers all of this for 30 days without a card. Setup guides for Nagios, Zabbix, PRTG, UptimeRobot, Synology NAS, Microsoft 365 rules and temperature sensors are on the works with page, and the mechanism end to end is on how an email becomes a phone call.