The UA1 project began in 1976; the idea was to detect the communicators of weak interaction (W and Z bosons), which has been postulated but never observed.
UA1 and UA2 experiments started again in September 1982 until December 1982, when the accelerators were switched off for two months.
The central part of the UA1 detector is exposed in the Microcosm since 1999.
UA1 invites UA2 to a session with the Resource Priority level of 3 (levels 1 and 2 are higher is this domain, and the namespace element is not necessary for this discussion).
UA1 invites UA2 to a session with the Resource Priority level of 3 (levels 1 and 2 are higher in this domain) and is accepted.
After the session between UA1 and UA2 is established, UA3 invites UA2 to a new session with an R-P of 2 (a higher priority than the current session to UA1).
UA1 discovers P1 via DHCP (this is just an example, and other mechanisms besides DHCP are possible).
The mission is for UA1 to discover HSP so that outbound requests from UA1 may be routed (at the discretion of UA1) through HSP, thereby receiving outbound services from HSP.
Figure 1: Scenario for reconstituting call state UA1 is in domain foo, and makes a call which terminates at UA2 in domain bar.
The original INVITE from UA1 to UA2 passes through some number of proxies (potentially zero), and arrives at UA2.
Jonathan Rosenberg [Page 6] Internet Draft reconstitution July 13, 2001 Assuming there were no record-routing proxies, when UA1 tries the re-INVITE, it attempts to send the request to the SIP URL in the Contact header of the 2xx response to the initial INVITE.
However, due to network topology, UA1 must use P1 as an "outbound proxy", and all requests between UA1 and REGISTRAR must also traverse P1, P2, and P3 before reaching REGISTRAR.
UA1 discovers P1 as a result of configuration, DHCP assignment or other similar operation, also outside the scope of this document.
REGISTRAR inserts a preloaded Route toward UA1 and retargets the request by replacing the request URI with the registered Contact.
UA1 discovers P1 as a result of a DHCP assignment.
UA1 wishes to register with P2, using P1 as a default outbound proxy.
Note that if the relationship between UA1 and P1 is fixed and P1 is registration-stateful, P1 could store the draft-willis-sip-path-01 [Page 4] Internet-Draft Path Extension Header for SIP February 2002 response Path on the behalf of UA1 and insert it into future messages from UA1.
Although UA will determine the expiration period of subscriptions to it, the state agent may choose to refresh subscriptions on a more regular basis as an extra means of ensuring continuity of shared line service.
The discontinuation of the bridged line service within user agent UA1 is shown by the abrupt termination of the UA1 vertical time line.
Security Considerations Since many of these features are implemented using semantics provided by RFC 3261 [2], Event Package for Dialog State as define in [7], and Event Notification [4], security considerations in these documents apply to this draft as well.
Background 3GPP established a requirement for discovering intermediate proxies during SIP registration and published this requirement in draft- garcia-sipping-3gpp-reqs [5].
Likewise, all requests between REGISTRAR and UA1 must also traverse P3, P2, and P1 before reaching UA.
We have extended the diagram from the previous example by adding UA2, and by showing P2 out-of-line indicating that it did not include itself in the path during registration.
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UA1 discovers P1 via Dynamic Host Configuration Protocol (DHCP) (this is just an example, and other mechanisms besides DHCP are possible).
Please note that some header fields (e.g., Content-Length) and session descriptions are omitted to provide a shorter and hopefully more readable presentation.
Example of Mechanism in INVITE Transaction This example shows the message sequence for an INVITE transaction originating from UA1 eventually arriving at UA2 using outbound services from HOME.EXAMPLE.COM.
The mission is for UA1 to discover HSP so that outbound messages from UA1 may be routed (at the discretion of UA1) through HSP, thereby receiving outbound services from HSP.
Discussion of Mechanism The proposed mechanism uses a private header "P-ServiceRoute" in the REGISTER response to indicate a service route that the UA may wish to use if requesting services from the proxy network associated with the registrar generating the response.
The service being provided by HOMEDOMAIN is a "speed dial" service, where the user's private speed dial code "Joe" is expanded to "sip:Joe@UA2" by the action of HSP.
> > UA1 failed call INVITE URL: > ====================== > INVITE sip:UA2@sip.sipcenter.com SIP/2.0 > > However, UA2 is that ua's Display Name, it registers as: > pikatech2@sip.sipcenter.com, i.e.
> > > > Your ua1 config file shows: > > > > Speed_Dial string #400 UA2@192.168.69.125:5077 > > #Speed_Dial string #400 pikatech2@sip.sipcenter.com > > > > I think that the second line should be the one used for a sipcenter call, > > while the first look like a ua->ua URL.
> > > > I can only make calls from ua1 to ua2 via proxy server if ONLY ua2 is > > > > registered.
***************************************************************** 1541 CHIPS VS SYMPTOMS PCB# 1540050 (early version) with ALPS drive mechanism (1982) UA1 74LS14 LOGIC When drive powered up, red LED stays on and spindle motor runs continuously.
CR3 2 AMP 200V BRIDGE RECTIFIER (FOR +5V) On power up, green and red LED's are dim or dark and spindle motor runs continuously.
****************************************************************** 1541 CHIPS VS SYMPTOMS PCB# 251830 or 251777 with Newtronics drive mechanism (1984) UA1 74LS14 LOGIC When drive powered up, red LED stays on and spindle motor runs continuously.
Willis & Hoeneisen Standards Track [Page 2] RFC 3327 Path Extension Header Field for SIP December 2002 Eventually, REGISTRAR or a "home proxy" (a proxy serving as the terminal point for routing an address-of-record) closely related to it will receive a request destined for UA1.
5.5.1 Example of Mechanism in REGISTER Transaction As an example, we use the scenario from the Background section: UA1----P1-----P2----P3-----REGISTRAR Willis & Hoeneisen Standards Track [Page 7] RFC 3327 Path Extension Header Field for SIP December 2002 In this example, UA1 sends a REGISTER request to REGISTRAR.
Message sequence for REGISTER with Path: F1 Register UA1 -> P1 REGISTER sip:REGISTRAR.EXAMPLEHOME.COM SIP/2.0 Via: SIP/2.0/UDP 192.0.2.4:5060;branch=z9hG4bKnashds7 To: UA1
