U1900 and the original traditional PBX can be connected through () to protect customers' early investment () (Multiple choice)

Regarding the H.225 call signaling process, the following message sequence is wrong ()

In the U1900+SC solution, if a conference reservation is made through SMC2.0 and a multi-party telephone terminal is called, the following statement is correct () multiple choice

Regarding the characteristics of single-node networking, which statement is correct () (single choice)

In the message classification of the RTCP protocol, which of the following messages describe the receiving statistics data of the receiving gateway? ()