If you are getting Modem status: Unknown or Disconnected, please check modem log.
You can do it in menu Settings > Sysinfo tab > Gammu log
Tue 2015/05/05 18:22:13 gammu-smsd[3632]: ERROR: phone requires not supported code type: Unknown error. (UNKNOWN[27])
Tue 2015/05/05 18:22:13 gammu-smsd[3632]: Terminating communication...
It means that your SIM-card needs PUK number.
You have to put card inside some cellphone and unlock it. Then it should work in SMSEagle gateway.
Alternative option to unlock SIMcard is to use built-in gammu tool:
gammu entersecuritycode PUK {PUK_code} {new_PIN_code}
For example:
gammu entersecuritycode PUK 12345678 1234
(first you've to kill gammu with killall gammu-smsd)
Above will work only for NPE devices. If you've got NXS device, you need to specify config file:
gammu -c /etc/gammu-smsdrc1 entersecuritycode PUK 12345678 1234 (for modem #1)
gammu -c /etc/gammu-smsdrc2 entersecuritycode PUK 12345678 1234 (for modem #2)