random call disconnect -- can somebody help me investigate why this happens

[sims]

this has happened several times before. this time i was near the computer and i captured the log from the time when it happened. i can see something is going on, but i cannot understand what happened. thanks!!
---
[Oct 14 11:56:32] DEBUG[6079] app_macro.c: Executed application: GotoIf
[Oct 14 11:56:32] VERBOSE[6079] logger.c: -- Executing [s@macro-dialout-trunk:19] GotoIf("SIP/103-b79073d0", "0?customtrunk") in new stack
[Oct 14 11:56:32] DEBUG[6079] app_macro.c: Executed application: GotoIf
[Oct 14 11:56:32] VERBOSE[6079] logger.c: -- Executing [s@macro-dialout-trunk:20] Dial("SIP/103-b79073d0", "SIP/vitel_360/18005446666|300|tT") in new stack
[Oct 14 11:56:32] VERBOSE[6079] logger.c: -- Called vitel_360/18005446666
[Oct 14 11:56:32] VERBOSE[6079] logger.c: -- SIP/vitel_360-09a08570 answered SIP/103-b79073d0
[Oct 14 11:58:17] VERBOSE[6033] logger.c: == Spawn extension (macro-dial, s, 7) exited non-zero on 'SIP/ms-b7903458' in macro 'dial'
[Oct 14 11:58:17] VERBOSE[6033] logger.c: == Spawn extension (macro-dial, s, 7) exited non-zero on 'SIP/ms-b7903458' in macro 'exten-vm'
[Oct 14 11:58:17] VERBOSE[6033] logger.c: == Spawn extension (macro-dial, s, 7) exited non-zero on 'SIP/ms-b7903458'
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [h@macro-dial:1] Macro("SIP/ms-b7903458", "hangupcall") in new stack
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:1] ResetCDR("SIP/ms-b7903458", "w") in new stack
[Oct 14 11:58:17] DEBUG[6033] app_macro.c: Executed application: ResetCDR
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:2] NoCDR("SIP/ms-b7903458", "") in new stack
[Oct 14 11:58:17] DEBUG[6033] app_macro.c: Executed application: NoCDR
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:3] GotoIf("SIP/ms-b7903458", "1?skiprg") in new stack
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Goto (macro-hangupcall,s,6)
[Oct 14 11:58:17] DEBUG[6033] app_macro.c: Executed application: GotoIf
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:6] GotoIf("SIP/ms-b7903458", "1?skipblkvm") in new stack
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Goto (macro-hangupcall,s,9)
[Oct 14 11:58:17] DEBUG[6033] app_macro.c: Executed application: GotoIf
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:9] GotoIf("SIP/ms-b7903458", "1?theend") in new stack
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Goto (macro-hangupcall,s,11)
[Oct 14 11:58:17] DEBUG[6033] app_macro.c: Executed application: GotoIf
[Oct 14 11:58:17] VERBOSE[6033] logger.c: -- Executing [s@macro-hangupcall:11] Hangup("SIP/ms-b7903458", "") in new stack
[Oct 14 11:58:17] VERBOSE[6033] logger.c: == Spawn extension (macro-hangupcall, s, 11) exited non-zero on 'SIP/ms-b7903458' in macro 'hangupcall'
[Oct 14 11:58:17] VERBOSE[6033] logger.c: == Spawn extension (macro-hangupcall, s, 11) exited non-zero on 'SIP/ms-b7903458'
[Oct 14 12:19:17] VERBOSE[6079] logger.c: == Spawn extension (macro-dialout-trunk, s, 20) exited non-zero on 'SIP/103-b79073d0' in macro 'dialout-trunk'
[Oct 14 12:19:17] VERBOSE[6079] logger.c: == Spawn extension (macro-dialout-trunk, s, 20) exited non-zero on 'SIP/103-b79073d0'
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [h@macro-dialout-trunk:1] Macro("SIP/103-b79073d0", "hangupcall|") in new stack
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:1] ResetCDR("SIP/103-b79073d0", "w") in new stack
[Oct 14 12:19:17] DEBUG[6079] app_macro.c: Executed application: ResetCDR
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:2] NoCDR("SIP/103-b79073d0", "") in new stack
[Oct 14 12:19:17] DEBUG[6079] app_macro.c: Executed application: NoCDR
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:3] GotoIf("SIP/103-b79073d0", "1?skiprg") in new stack
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Goto (macro-hangupcall,s,6)
[Oct 14 12:19:17] DEBUG[6079] app_macro.c: Executed application: GotoIf
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:6] GotoIf("SIP/103-b79073d0", "1?skipblkvm") in new stack
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Goto (macro-hangupcall,s,9)
[Oct 14 12:19:17] DEBUG[6079] app_macro.c: Executed application: GotoIf
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:9] GotoIf("SIP/103-b79073d0", "1?theend") in new stack
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Goto (macro-hangupcall,s,11)
[Oct 14 12:19:17] DEBUG[6079] app_macro.c: Executed application: GotoIf
[Oct 14 12:19:17] VERBOSE[6079] logger.c: -- Executing [s@macro-hangupcall:11] Hangup("SIP/103-b79073d0", "") in new stack
[Oct 14 12:19:17] VERBOSE[6079] logger.c: == Spawn extension (macro-hangupcall, s, 11) exited non-zero on 'SIP/103-b79073d0' in macro 'hangupcall'
[Oct 14 12:19:17] VERBOSE[6079] logger.c: == Spawn extension (macro-hangupcall, s, 11) exited non-zero on 'SIP/103-b79073d0'
[Oct 14 12:19:25] WARNING[4230] chan_sip.c: Remote host can't match request BYE to call '[email protected]'. Giving up.
[Oct 14 12:20:16] VERBOSE[4214] logger.c: -- Remote UNIX connection
[Oct 14 12:20:16] VERBOSE[6218] logger.c: -- Remote UNIX connection disconnected
[Oct 14 12:20:16] VERBOSE[4214] logger.c: -- Remote UNIX connection
[Oct 14 12:20:17] VERBOSE[6222] logger.c: -- Remote UNIX connection disconnected