We need some more information to help diagnose this.
1) I see that it happens for both internal and external callers. Is there any transcoding (ie, are some callers in G.729 and some in G.711 regions) in the network, and does it only happen on callers for which there is transcoding? Are there gateways to the PSTN or other phone networks, and does it only happen for calls over gateways? Is CCM the only phone integration or is there also a circuit-switched PBX?
2) Have you received any reports from the callers how got cut-off, or just from the people who've received the truncated message? If you have received reports from people who were cut-off, did they say if Unity had hung-up on them or if Unity had stopped recording and gave them a prompt? Or, similarly, have people who got cut-off called back and said, "Unity hung-up on me or interrupted me and started playing prompts"? That matters, since what likely happened is that either Unity thought there was disconnect tone (which would cause the hang-up issue) or Unity thought there was silence (which would cause Unity to stop the recording and play a prompt to the user). Sometimes, a woman's voice might get interpreted as a disconnect (since many women have voices that are at a similar pitch to telephony tones), or sometimes a poor connection over the PSTN or from a cell phone might fade out and get cut-off. Also, sometimes silence can be incorrectly detected if people speak softly or record messages over a speaker phone.
Basically, we need to try to narrow this down a bit more. There are Unity traces that you can turn on which will show why each recording stops (caller presses a digit key, silence occurs, disconnect occurs, or recording limit is reached). However, that's really only useful if you know exactly when a caller was cut-off (meaning, they call and tell you exactly when) - it's often difficult to figure out which recording it was if they only report you get is from the person who receives the message. Also, if you can figure out a pattern (ie, calls over a gateway, between codec regions, etc.), then you can try to reproduce it on demand, and at that point try to get traces.
