Can pure SIP support video conference function?Somewhere, it mentions SIP does not. Then how do make a video conference by SIP. Co-operate with other protocols?by the way, which codecs does SIP use in the video confernece. I only know that in H.323, ...

It is always said H.323 is complex and SIP is simpler. Why?1. The component there are new components in H.323. but there are also new components like proxy server, redirect server in SIP.2. The protocols H.323 could co-operate with other ITU stan...

1.The centralized intelligence of the WLAN controller is because of the protocol LWAPP, right?2.I was wondering what is the difference of the LWAPP, and traditional access point transmission protocol (is there any protocol like APP)?3.I know the feat...

1. POTS is totally analog and circuit switched. ISDN is totally digital and packet switched. How about PSTN, digital and packet swtiched???? One difference of them is the speed. from POTS to ISDN, the data rate is faster and faster. right?! Any other...

First~~~ please do not be mad with me.since my questions sound some how stupid.1. We use gateway between PSTN and IP network. But in PSTN, the voice is analogue. But in IP network, the data is digital. Which role does gateway act? The D/A converter,...