5/H.450.4 states that it is an implementation/application matter which of the two hold scenarios (near or far end) is invoked. It does, however, not state whether it is mandatory to implement both, any of the two or one particular scenario. Which is the case? The fact that 10.2/H,450.4 mandates that a Gatekeeper/Proxy passes near end call hold messages on to the held endpoint would seem to mandate that at least the near end scenario has to be supported.

5.1/H.450.4 states that the holding endpoint "has to" stop receiving and sending user packets. There is, however, no "shall" in the sentence. Should this then be treated as mandatory? Furthermore, what does it actually mean? To stop receiving can, e.g., mean that received packets are not passed on to the user. The section then continues with a number of MOH options, the last of which is "other indications". This is extremely vague when considering that 7.1.1/H.450.4 mandates that MOH be provided. Does "other indications" include doing nothing?

7.1.1/H.450.1 mandates that MOH be provided to the held user. Why is MOH a mandatory requirement?

7.2.1/H.450.4 states that if the response to a holdNotific.inv or a retrieveNotific.inv, while in the state Hold_NE_Held, is a reject APDU, this shall be _ignored_. The first means that the originating endpoint (or rather its user) simply (and falsely) assumes that the remote party is on hold. Ignoring the second, means that originating party does not restore its state to Hold_Idle! The section then state that user B knows about the hold condition because of the MOH. How can it be guaranteed that the MOH is such that it is recognised as such?

10.1/H.450.4 is about remote-end call hold. Nevertheless, it states: "The proxy in this case shall act as a held endpoint for remote-end call hold and may act as a served endpoint for _near-end hold_". Should the part about near-end hold be interpreted as applying to the role it plays towards the held endpoint?

10.2/H.450.4 states that the near-end call hold messages _shall_ be passed on to the held endpoint. Why isn't it allowed to use remote end call hold on the held side?

Frank

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