| No, that is the role of a resource reservation protocol. There is no reason to assume that any Internet telephony signaling server (such as a proxy) would know the available bandwidth in real networks. Having such a central server would not scale. Administering bandwidth separately for each application is also likely to be difficult and inefficient.
There is a proposal for an SDP extension that allows SIP INVITE requests and responses to indicate that resource reservation must succeed before the callee is alerted. Several proposals can also be found at http://www.cs.columbia.edu/~hgs/sip/drafts_qos.html.
2000-Jul-03 7:55pm islepchin@dynamicsoft.com |
SIP FAQ : 
Does SIP do admission control?