How to make Zabbix call on critical alerts?

Hi All,

I would like to know how to make my Zabbix 2.0.0 make a call when critical alerts happen. For e-mails and SMS, i already have implemented, and it works fine.

I have found some options like TWILIO, but i would like to use my internal infrastructure. I have a GSM card for the SMSs, if possible i would like to use it to do the calls, or even use my Cisco CallManager.

So please share your opinions/options...

Thank you