[SIPForum-discussion] General SIP Server Question

Wed Aug 27 15:29:51 UTC 2008

Comments Inline.
--VB

On Wed, Aug 27, 2008 at 4:46 PM, 杨伟 <shyw13 at gmail.com> wrote:

> I am not clear.
>
> I want it step by step.
>
> First, If the proxy(registrar) and outbound proxy operate seperately, that
> is we just have a proxy or a outbound proxy. Do they serve the same
> function?
>

Definitely not. They don't serve the same function. Since outbound is
serving the service for multiple domains, it simply forward the request to
proxy responsible for that domain.

>
> They both will receive the Register message, and record the location of the
> UA?
>

No. Outbound has no information about the location of UA.

>
> Also Invite messages will be sent to them, when the UA want to make a call?
>

Yes. Outbound will query the proxy/ registrar for the current location of
the UAS and send the INVITE accordingly.

I am not sure whether any RFC/ Standard is there or not for the signaling
between Outbound and Proxy. May be someone can help us on the same.

>
>
>
>
> 在08-8-27，Vivek Batra <vivek7683 at gmail.com> 写道：
>
>> Hi,
>> Yes, it leads to confusion when you consider both **proxy** and outbound
>> proxy at the same time.
>>
>> First of all, should we say it proxy or registrar?? No matters since
>> different UA manufactures call by different name. E.g., Look at the
>> configuration of Linksys UAs and Grandstream, you will found it by name
>> Proxy however in Vodtel, Matrix etc, you will found by name Registrar.
>> Name of Outbound in UA configurations remain the same.
>>
>> Now why we need proxy (or registrar) when we have outbound? I believe that
>> we need because of following:
>>
>> 1. NAT Traversal
>> 2. Support multiple domains (much required in ITSP business)
>>
>> First requirement can also be served by not having any outbound proxy. We
>> can have only proxy (or registrar) in the same box only.
>>
>> But in the second requirement, two separate logic modules are required to
>> maintain the call control (signaling/ media) which is handled by outbound
>> proxy and to maintain the location service which is handled by proxy (or
>> registrar).
>> In those scenerios, proxy (or registrar) address just acts as tag in the
>> SIP message which identifies the User Domain. However, it is possible that
>> the proxy (or registrar) is configured in the same box in which outbound is
>> configured.
>>
>> You can see various ITSP's providing this type of service. Suppose you
>> have company with URL kapanga.com. Now u need SIP number for each
>> employee in your company. What generally ITSP do in this case is, providing
>> you numbers like employee1 at kapanga.com, employee2 at kapanga.com etc etc.
>> Now kapanga.com serves you as proxy server address (or registrar server
>> address). This address does not need to be resolved by global DNS server
>> since your ITSP would also provide you Outbound Proxy Address also.
>>
>> Now you communicate only with the Outbound of your ITSP, however you
>> provide your domain information in the SIP message (FROM, TO etc). Outbound
>> address is only used upto netowrk layer. Proxy address (or registrar
>> address) serves you on application layer.
>> Doing this, outbound identifes the domain (e.g., Kapanga.com in this case)
>> it serves.
>>
>> I hope, this would give some idea however please do give your feedback.
>>
>> --VB
>>
>>
>>
>> On Tue, Aug 26, 2008 at 7:47 AM, 杨伟 <shyw13 at gmail.com> wrote:
>>
>>> Hi, Vivek
>>>
>>> I am a little bit confused with case 3.
>>>
>>> In case 3, both Proxy address and  outbound proxy address are set. I
>>> could not any possibility a message will be sent to the Proxy. So it is not
>>> used?
>>>
>>>
>>> 2008/8/14, Vivek Batra <vivek7683 at gmail.com>:
>>>
>>>> Jerry,
>>>> Following possibilities are there in each SIP Phone.
>>>>
>>>> 1. When you configure only registrar address (or proxy address), SIP
>>>> phone sends the registration request and call request (INVITE etc) only to
>>>> registrar/ proxy address configured.
>>>>
>>>> 2. When you configure only outbound proxy address in SIP Phone (and not
>>>> registrar/ proxy address), SIP phone does not sends any registration request
>>>> however all other messages are send to outbound server only.
>>>>
>>>> 3. When you configure both registrar/ proxy and outbound proxy address,
>>>> all registration request and call request is send to outbound server only on
>>>> IP layer however the request is sent for specific domain only (which you
>>>> have been configured as registrar/ proxy address).
>>>>
>>>> Difference between case1 and case3 is, you have not set the outbound in
>>>> case1 while it is in case3. Hence, in cas1, if registrar/ proxy server
>>>> redirect you to some other domain, SIP Phone tries to send the request to
>>>> redirected domain only. However, in case3, you have been set the outbound,
>>>> hence if outbound redirect you to some other domain, then also SIP phone
>>>> sends the new request to same outbound only which is configured.
>>>>
>>>> Hence, the name of SIP entities depends on how you use it!!
>>>>
>>>> Cheers!
>>>> Vivek
>>>>
>>>> On Wed, Aug 13, 2008 at 10:45 AM, Jerry Richards <
>>>> jerryr at tonecommander.com> wrote:
>>>>
>>>>> Hello All,
>>>>>
>>>>> General question regarding a SIP phone configuration where the phone
>>>>> communicates with a single SIP server.  Would you agree such a phone
>>>>> need
>>>>> only configure the following two SIP server entities?
>>>>>
>>>>> 1) SIP Registrar (either IP-address or domain-name) to be used inside
>>>>> the
>>>>> SIP messages for both registration and call-control.
>>>>>
>>>>> 2) SIP Proxy (either IP-address or domain-name) to only be used to
>>>>> identify
>>>>> where SIP messages are sent.  Basically, this is an Outbound Proxy.
>>>>>
>>>>> RFC 3261 uses Proxy and Outbound Proxy and Registrar as if there are
>>>>> three
>>>>> entities, so I'm a bit confused.
>>>>>
>>>>> Best Regards,
>>>>> Jerry
>>>>>
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>>>>>
>>>>
>>>>
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>>>>
>>>
>>
>
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