Re: [sr-dev] about contact params

2010/11/26 Juha Heinanen &lt;jh(a)tutpro.com&gt;om>: Juha, I can ensure you that I'm right, I studied it a lot some time ago. In fact, Contact has similar syntax than From header (but Contact allows various entries separated by comma). It's very common to see the following From format: From: sip:alice@domain.org;tag=qweqwe For sure, Fromtag MUST be a header param and not a URI param (as Fromtag is defined to be a header param in RFC3261). RURI is a addr-spec, so any param in the RURI is, of course, a URI param. But in case a From/Contact/To header contains a addr-spec then a param is ALWAYS a header param. If you want to add a URI param in these headers you MUST user name-addr format. One more argument: contact-param = (name-addr / addr-spec) *(SEMI contact-params) Imagine you use addr-spec, you want a URI param ";uri-param=1234" and a header param ";header-param=9999". How would it look?: Contact: sip:alice@dom.org;uri-param=1234;header-param=9999 If you were right, how to determine that ;uri-param is a URI param and ;header-param is a header param? There is no way! So the only solution is using name-addr: Contact: <sip:alice@dom.org;uri-param=1234>;header-param=9999 This is a complex grammar in the RFC 3261, and there have been long discussions about it in sip-implementors maillist, you can search for them if you want. Yes, of course, but then it CANNOT contain URI params, just header params. Regards. -- Iñaki Baz Castillo &lt;ibc(a)aliax.net&gt;