txt.att.net is returning MX records and those machines don’t have port 444 open…
Wouldn’t you want to be sending something like a SNPP message instead? It’s a much less convoluted delivery process and is almost real-time (no queuing).
I guess it’s been a decade or so since I’ve dealt with emergency services and paging…is SNPP even a thing anymore?
I looked at some old code I wrote (https://github.com/darkpixel/snppsend/blob/master/more-providers), and it doesn’t look like snpp.attws.net exists.
-A