Asterisk & OfficeServ500

There are Samsung OfficeServ500 and Asterisk (CentOS 5.4 64 bit). If we use SIP-phones everything works well. But if we use IAX-phones there is an following trouble: after the unpredictable period of time subscribers iax cease to hear subscribers Officeserv

MGI2 voip-cards works bad
MGIN voip-cards works well

We will be try to upgrade MGI2 voip-cards software

Could you please describe your situation a bit more, you didnt say how you were using Asterisk and the OfficeServ. We are not able to help you until you provide more info, and actually ask a question, you more or less just made a few statements.