> Is it possible to transfer a call without using SIP REFER. > Call path: > [uac]-------[sip proxy]--------[uas] > The SIP REFER is not supported in the above sip proxy.
As indicated by RFC 3261 section 16.3, the proxy does not need to support REFER. It just needs to proxy the REFER. " This protocol is designed to be extended. Future extensions may define new methods and header fields at any time. An element MUST NOT refuse to proxy a request because it contains a method or header field it does not know about." Thus if the proxy does not relay the REFER to the UAS, it is either non-compliant or providing a service (such as helping referred party avoid a potential unexpected billing situation). > Is there a way to achieve call transfer without using sip refer... Yes; BYE with Also might still work with some older devices. :) https://tools.ietf.org/html/draft-ietf-mmusic-sip-cc-01 The REFER is the SIP way to trigger a transfer. Most of the other ways are proprietary, RFC 3725 type stuff, or things such as the transfer described within RFC 4730 section 3.4. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
