Basically your local phone service provider can not see what your CCM is doing with the call on the second transfer. To them it looks like a new call, thus you are getting charged for the second transfer, if there are any costs involved (i.e long distance).
Besides having a CCM, I also have a Nortel SL-100, on that PBX when you assign call transfer to a phone, you have the option of defining the call transfer capabilites as "call transfer all or call transfer intra-group, in other words restricted to the PBX". This is how we restrict most phones from transferring back off the PBX and incurring costs. Most users don't realize that if they receive a call from the PSTN, then in turn transfer the call back to the PSTN that they will incur the cost of the second if there is any associated costs. I don't believe CCM has the capabilities to restrict call transfer so what you have is a user training problem to make them aware of the danger of call transfers to long distance numbers.
You can block OffNet transfers with a CCM service parameter. Goto CCMAdmin->Service->Service Parameters->CallManager Service and adjust the below parameter to True. This is a global setting and will affect all calls to all phones that have a call marked as offnet. This might affect not just PSTN gateways if you have VOIP gateways with calls being marked as OFFNET vs. OnNET.
Block OffNet To OffNet Transfer : This parameter determines whether transfers between external (OffNet) parties are blocked (not allowed). Valid values specify True (block transfers between OffNet parties) or False (allow transfers between OffNet parties).
The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...
This document describe how DST changes and how time changes are
implemented in DST. Daylight Saving Time (DST) is the practice of
setting the clocks forward 1 hour from standard time during the summer
months, and back again in the fall, in order to make b...