So it was working for several days without error then tonight while I'm watching users login to the modem pool - BOOM! The sync changes when it happens (which makes sense). Zaptel: Master changed to Tor2/0/2 Zaptel: Master changed to Tor2/0/1 Zaptel: Master changed to Tor2/0/2 Zaptel: Master changed to Tor2/0/1 Interrupts should not be a factor THIS time: [root@phone asterisk]# cat /proc/interrupts CPU0 0: 49007934 XT-PIC timer 1: 16 XT-PIC keyboard 2: 0 XT-PIC cascade 5: 4014360 XT-PIC eth0 8: 1 XT-PIC rtc 11: 490107958 XT-PIC tor2 14: 730932 XT-PIC ide0 15: 0 XT-PIC ide1 NMI: 0 ERR: 0 Errors are too familiar! Dec 15 21:01:40 NOTICE[566]: chan_zap.c:7494 pri_dchannel: PRI got event: HDLC Abort (6) on Primary D-channel of span 1 Dec 15 21:01:40 WARNING[566]: chan_zap.c:7246 zt_pri_error: PRI: Short write: -1/15 (Unknown error 500) Dec 15 21:01:40 WARNING[566]: chan_zap.c:3202 zt_handle_event: Detected alarm on channel 1: Red Alarm -- Hungup 'Zap/25-1' Dec 15 21:01:40 WARNING[566]: chan_zap.c:5791 handle_init_event: Detected alarm on channel 2: Red Alarm Dec 15 21:01:40 WARNING[566]: chan_zap.c:5791 handle_init_event: Detected alarm on channel 4: Red Alarm ... The server is dedicated to asterisk.. not much else is going on. Anyone have some recommendations for me? I'm thinking about replacing the motherboard. Thanks, -- Andrew McRory - President/CTO Linux Systems Engineers, Inc. - http://www.linuxsys.com Located in beautiful Tallahassee, Florida Office 850-224-5737 Office 850-575-7213 Mobile 850-294-7567