When looking at the Mitel protocol Specification from the 3CX Website, it clearly states the following: 3CX PMS Protocol Specification On this topic · Introduction · Micros FIAS Vendor Record Specification Form · Mitel General Protocol Information · PMS to System Transmission · PMS Format Specification · Check In/Out Messages · Name Message · Wake Up Messages · DND Message · Message Registration Message · Message Waiting Message · Station Restriction Message · Maid Status Message · Mini Bar Message When examining the specification with regard to Station Restriction 3CX published the following: Station Restriction Message A Station Restriction message can be used to establish call restrictions. When this message is sent from the PMS to the system, it brings previously programmed Call Restrictions into effect. Note: Emergency Services (911/999) and internal calls are never restricted. The Station Restriction message has the following format: RST: Is the Station Restriction function code. X: Is an extension or suite number digit. S: Is one of the following status codes: · 0 - Internal · 1 - Local · 2 - Long Distance StxValue = 2 EtxValue = 3 ENQ = 5; ACK = 6; However, despite the specification indicating support for the above, such is not the case. 3CX does not have the ability to respond as stated with regard to any calling restrictions other than to restrict to internal (block or unblock) calls. They do support RST0. There are no current plans to support the other restriction codes and when queried about correcting the "specification" to reflect what the system will support so as to prevent others from having the same misunderstanding, I was informed that "no change of the documentation was deemed necessary. That's something you would need to take to 3CX Ideas which is the appropriate channel for changes requests." It is beyond me as to why 3CX would think that anyone reading their page would not think the specification to be accurate and somewhat arrogant that they do not consider it to be to everyone's benefit to correct the documentation to reflect that which is indeed supported. So here it is as they suggested.