IPCC calls went to voice mailbox while dialing the TOLL FREE NUMBER

Question

Hi All,
We have an Cisco Call Manager & an IPCC server through which the cisco agent desktop users login & receives calls from the client. As you know the calls will route based on the Agents Login Activity/Availability. The clients dials the Toll Free number 866-123-4567 & the calls in-turn will route to 410-123-4567 & lands to one of the Cisco IP Phone IPCC extension.  Unfortunately today between 0700 & 1030hrs EST, all the clients whomsoever dials the toll free number, the calls goes to the voice mailbox & not to any of the Cisco IP Phone extension. The mystery is, when the client dials 410-123-4567, the calls will land to Cisco IP Phone IPCC extension to one of the user which is normal.
Problem while dialing to the toll free number. Any ideas/clues? No changes made on the CCM/IPCC in the recent days.
The issue happened today between 0700 & 1030hrs EST as mentioned earlier.

Answer 1

Hi Abu,
I use CCM-ver.4.1. I did not set any call forward option. Here is how the actual call takes place.
Client dials -> 866-123-4567 or 410-123-4567 & then dials the extension 3319 for the support team. 3319 will inturn route to 4319 & looks in for any agent logged in & then routes the calls to their cisco ip phone extension.
Client -> 866-123-4567 -> 3319 -> 4319 -> 5101 or 5102 or 5103
Client -> 410-123-4567 -> 3319 -> 4319 -> 5101 or 5102 or 5103
866-123-4567 is the toll free number which will be forwarded by the Telephone service provider to 410-123-4567 (866-123-4567 -> 410-123-4567)
From the PSTN, the calls land on to the cisco router codec used on the CCM is G.711