Release notices by email? By email from an unofficial email address? By unencrypted, undigitally-signed email from an unofficial email address?
"Phone calls" are remnants of the old century. Stop using cellphone services and use wi-fi only.
Um, that might work if you never leave the city. Some of us like to actually leave the city and go places where there might possibly be a cellphone signal, but there definitely ain't no wi-fi. Actually, my last real vacation was sufficiently out there that there wasn't hardly any radio, much less cellphone or internet. Surprised how little I missed it all.