Packetizer Forums: Session Initiation Protocol (SIP)

Re: Send SIP re-INVITE without SDP

2024-09-05T13:38:11Z

To determine which cases a re-invitation can be sent without SDP, you will need to refer to the SIP protocol documentation and consider specific cases, especially for responses such as 488 or 491. Santo handles can use SDP included or excluded based on call flow, other connection requirements, or response format . Looking at the call signaling log will help clarify when SDP should be added.

Send SIP re-INVITE without SDP

2013-12-02T09:31:10Z

From what i read a re-invite can be sent without SDP but not in all cases. How can i find which are those cases?
More specific, i want to know if re-invites that are followed up with a 488 or a 491 response are supposed to send SDP.

Re: SIP is not an emerging protocol

2012-10-09T05:16:30Z

Yes maybe paulej you are right, I can see your point.
I wrote it is emerging, yes because the people, the non-nerds :) like me never heard about it and I just discovered it lately and most of my friends started to use it not long ago. But yes according to your point of view it is not emerging.
I like your reasoning. :)

Re: SIP is not an emerging protocol

2012-10-08T20:53:03Z

I don't think this negates the fact that SIP is not an "emerging" protocol. The protocol has emerged a long time ago. Many people have not heard of it, because they're not nerds. People have used the PSTN for decades, but most have never heard of SS7, either. Does that make SS7 emerging? Hardly.

Now, SIP having issues is a whole other topic. In the famous words of a friend of mine, "SIP sucks. It really sucks. But, it's what we have." SIP is not the best solution for migrating the world away from the PSTN, but it's an acceptable first step. Anything beyond basic voice presents challenges for SIP. Hell, even basic voice calls present challenges for SIP. Suppose my phone prefers G.729 and yours prefers iLBC and does not support G.729. If I call you, my phone would offer G.729 and your phone would reject the call. Well, that's pretty useless, isn't it?

So, my phone will then try to place a second call, this time offering G.711. Your phone probably supports G.711, so we can communicate. However, my phone might also support iLBC, but that codec would never be selected since I have no idea what capabilities your device supports.

In this respect, H.323 is significantly superior to to SIP. H.323 is also better for video, since video codec negotiation is a much more complex exercise. It's important to have a good capability exchange mechanism.

And, we're getting to a point now where anyone can set up their own H.323 video service that runs "over the top" on the Internet. I can be reached at h323:paulej@packetizer.com or h323:paulej@cisco.com. The former is powered with a GnuGK and the latter is powered by Cisco's VCS and CUCM. Note that some people still have NAT/FW issues, but there are solutions to NAT/FW traversal. We have information on how to set up and manage your own H.323 services interconnected with the rest of the world at http://www.h323.net/. Spranto also provides free calling services like Skype for those who just want to download the client and give it a try. It's free, too.

Re: SIP is not an emerging protocol

2012-10-08T08:00:31Z

SIP-based infrastructures are reliable that provide good quality.
I would also say it is emerging because there are still a lot of people who havent heard about it.
I would like to show you a page with a description on SIP:
http://ozekiphone.com/what-is-sip-session-initiation-protocol-310.html
This page also consists of a video that represents how it is connected to Ozeki Phone System XE.

Re: SIP is not an emerging protocol

2011-10-18T06:14:55Z

well, the PSTN users don`t even know VOIP but they are still using it this is the same as many of users uses SIP but they don`t know about it. but both of the technologies are in use
Thanks

Re: help with SIP compatability

2011-10-14T12:33:31Z

Thanks for the fast reply! This really helps clear up how the VoIP system will work. I think this will help make the sale.
Thanks again! :D

Re: help with SIP compatability

2011-10-14T01:57:56Z

Hello, I am working for a telephone reseller (ESI) and I have a client that needs a specific 'secure' IP phone (TEO) and I want to make sure our comm server will talk to the phone via SIP/VoIP.

I'm not sure what TEO is. A brand?

Is only one codec (G.711) needed, or do all need to match up between phone and server?

One only needs one codec to match. However, many SIP devices will only offer one codec. The codecs usually chosen are G.711 or G.729, depending on available bandwidth to the phone. For the public Internet or bandwidth-contrained branch offices, use G.729. For communication over the LAN in an enterprise, use G.711. (If you have WAN links with plenty of bandwidth, use G.711. The audio quality is better.)

if both have 802.1q and DiffServ, do they also both need UDP and DHCP?

This question does not make sense to me.

802.1q is for VLAN support.[/*]
DiffServ is for indicating the class of service in an IP packet.[/*]
UDP is the protocol most commonly used to send media packets.[/*]
DHCP is a protocol for assigning dynamic IP addresses.[/*]

They all serve a different purpose.

does 802.1p on the server side help or hinder a phone without that?

This is for indicating priority of packets at layer 2. So, I don't understand what you mean by having a server side.

Thanks for the help, I know nothing about this type of protocall so please help me understand. :)

Folks on this board know this stuff, but I fully appreciate how overwhelmed you might be just getting into this area. It's definitely interesting to learn, but it will take a little time and it might be useful to get a book from Cisco on VoIP fundamentals. The information you might want to know is around the Internet, but having a good book with a lot of the background information would be helpful.

I'm happy to help answer questions, but it's hard to answer questions that are broadly scoped. If you were to ask me about specific messages or flows in H.323 or SIP, for example, that would be easier :-)

help with SIP compatability

2011-10-13T20:31:17Z

Hello, I am working for a telephone reseller (ESI) and I have a client that needs a specific 'secure' IP phone (TEO) and I want to make sure our comm server will talk to the phone via SIP/VoIP.

Is only one codec (G.711) needed, or do all need to match up between phone and server?
if both have 802.1q and DiffServ, do they also both need UDP and DHCP?
does 802.1p on the server side help or hinder a phone without that?

Thanks for the help, I know nothing about this type of protocall so please help me understand. :)

Re: SIP is not an emerging protocol

2011-09-29T15:16:36Z

Thanks paulej for this information so what about VOIP Protocol , what would you say about voip technology?

VoIP in general is widely deployed now. It has become the standard technology used within virtually every larger enterprise and numerous service providers around the world. I would even say "most" service providers, but that might not be true. Certainly, every large service provider uses it.

So, VoIP is working well. It is everywhere, from the desktop to backbone carrier networks. Even people using normal PSTN lines are indirectly using VoIP and do not even know it. The legacy switched circuit network is being replaced.

Re: SIP is not an emerging protocol

2011-09-29T10:00:19Z

Thanks paulej for this information so what about VOIP Protocol , what would you say about voip technology?

Re: SIP is not an emerging protocol

2011-08-29T14:31:52Z

Now, the SIP trunking is the most emerging Technology, and it is used in business as well.
Thanks

Nobody disputes its use, but SIP is not "emerging". Neither is SIP trunking. More and more businesses might be adopting it, but that does not make it emerging. SIP has been around for 15 years! It is ancient technology now.

What is "emerging"? Web-based telephony protocols like the work in the IETF working group "RTC Web" and W3C's "Web RTC", as well as multi-device communication systems like the ITU's "Advanced Multimedia System". All of those are currently being defined and, with any luck, will start to be deployed over the next few years. That's emerging.

Re: SIP is not an emerging protocol

2011-08-29T11:41:24Z

Now, the SIP trunking is the most emerging Technology, and it is used in business as well.
Thanks

SIP is not an emerging protocol

2010-03-14T02:01:09Z

Why is it that after 14 years since the first publication of the SIP Internet Draft is it that people continue to refer to SIP as an "emerging" protocol? 14 years!?!?!

I herewith declare that SIP is NOT am emerging protocol.