[CentOS] funny SMS server tips

Hi guys,
Hehe.. I thought I want to share this.
In previous email, I said about monitoring server room.
I just realize that we have this quite old sms server appliance in the
room. It's still running though.
I want to setup cronjob from linux machines, to send mail to that sms
server, and it will then send sms to my cell about the machine
condition.
Problem is, nobody knows how to configure the sms server, and there's
no docs beside a little description in the web UI.
Been googling around few hours, but since it's quite old and
proprietary, no good result.

Problem is, the sms server's qmail refuses to work if I use hostname
in the mail like mycellnum at sms-server.
If I want to use mycellnum at 192.168.1.100, sendmail refuses to send it
as "host not found".
So, out of curiosity, I define this in this /etc/hosts:
192.168.1.100   192.168.1.100
And now sending from sendmail to mycellnum at 192.168.1.100 works!

is it a feature or what? In network convention, all-numeric hostname
is not allowed right?
Hehe.. anyway, now I can monitor my server room using sms.