2011/10/10 Alfred E. Heggestad aeh@db.org:
what is the relationship between gruu and outbound ? GRUU (RFC 5627) has a normative reference to Outbound (RFC 5626), probably because of +sip.instance. Outbound has an informative reference to GRUU spec.
IMHO Outbound is a real need (since NAT and TCP clients do exist), while GRUU is a cool feature, but not a requirement for the core protocol.