I would never trust SMTP for all the reasons already mentioned.  Primarily if my network is dead, I still want to get paged about it.  Relying on the import policy of another organization in the hostile port 25 environment is also bad voodoo.

We've used a mix of TAP and SMS for many years with varying success.  When the cell providers started dropping their TAP gateways, we went through a few GSM modems.  First a Nokia on a cable, but the thing would do dumb stuff like charge the battery, and with the cable connected go ahead and drain the cells unless someone walked by daily and reseated the power cord.  Avoid tethering phones, you will likely run into something to drive you nuts.  Next was a Sierra 750 PCMCIA GSM modem, which supported the standard AT command set (I forget the ANSI spec).  That was fine once overcoming the motherboard not assigning an IRQ, but once a week it'd stop responding to commands and have to be reseated.

The final, ultimately reliable setup, which I recommend, was a Falcom Samba 75 USB GSM modem (quad band) talking to smstools.  With unlimited SMS plans, two modems on separate networks, and some cron scripts, they could also monitor each other every hour to ensure they were sending and receiving pages.  We also did a daily "paging system is up on X" to oncall similar to what another poster mentioned.  Also we configured smstools to call an error script which'd send warnings another way (IRC in our case) if the modem wasn't responding as expected (failed to send, receive or init).

On 9/6/07, Rick Kunkel <kunkel@w-link.net> wrote:

Hello folks,

First off, apologies if this is off topic.  I'm hoping that system and
network monitoring tip are enough of a common issue that this falls under
the group's charter.

We've traditionally used mobile phone email addresses for system
notifications, but over the past 6-12 months, it seems to have become
increasingly sketchy.

For instance, if an application fails to contact a certain service on a
certain server, it sends an email (through it's own SMTP service, to avoid
a chicken-and-egg prob if/when our main SMTP service fails) to
1234567890@tmomail.net.  (Obviously, that was a fake number.)  More and
more, I'm getting less and less of these notifications.

It seems especially prevalent when MANY things are sent at once; if, for
example, a central piece fails, and dependent pieces suddenly fail as
well.

I try to telnet to mailx.tmomail.net port 25 and get sometimes good,
sometimes laggy, and sometimes no response.  T-Mobile, support levels all
the way up to 3 tell me that it's not them, and everything should work
wonderfully.

Is SMTP to a mobile phone a fundamentally flawed way to do this?

Anyone else have any issues, past or present, with this kind of thing?

Thanks,

Rick Kunkel