Introduction into SIP protocol

Brief introduction into SIP protocol, how it works, common problems to solve. Tech. details about handshake, SIP Trunks and SIP trunking. Market research.

1. What Michal knows about SIP? © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. For SolarWinds VNQM purposes internal use only

2. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP from 10 KM What is SIP and how it works? SIP troubleshooting SIP Trunking 2

3. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. What is SIP? In the world of VoIP, SIP is a call setup protocol that operates at the application layer. Designed to set up real-time multimedia sessions between groups of participants.  Can also be used to set up video and audio multicast meetings, or instant messaging conferences. Calls (voice or video) between SIP users are free, worldwide. There are no boundaries and no restrictive laws or charges. Contrasted with H.323, SIP is an exceedingly simple protocol . SIP Applications and SIP addresses are for FREE. 3

4. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. How SIP Works? You have to have SIP Address and Account (more details later) You have to have SIP Client (computer, mobile app, phone) You have to configure your SIP Client (via easy config wizard) You need a solid bandwidth – at least DSL connection You need to tell somebody else your SIP address  4

5. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Credentials Set during SIP provider registration. Must contain “@”. User name has to be unique (ideally email). Example how SIP credentials may look like: SIP address, e.g. [email protected] Password : e.g. NASYPMI Username: e.g. [email protected] Domain/Realm: e.g. thatsipservice.info Outbound proxy: e.g. proxy.proksi.com XCAP root: https://xcap.proksi.com/xcap-root 5

6. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Structure of SIP Address SIP:user@domain:port “user” – letters or a number “@” is mandatory! Splits user and domain. “domain” – service you are registering with. Could be name or IP Address “port” – is optional. Defines access on a proxy server. 6

7. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Let’s make a call! We are set now, we have SIP Address and configured client! 7

8. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Functions of SIP User location and registration End points (telephones) notify SIP proxies of their location; SIP determines which end points will participate in a call. User availability SIP is used by end points to determine whether they will “answer” a call. User capabilities SIP is used by end points to negotiate media capabilities, such as agreeing on a mutually supported voice codec. Session setup SIP tells the end point that its phone should be “ringing;” SIP is used to agree on session attributes used by the calling and called party. Session management SIP is used to transfer calls, terminate calls, and change call parameters in mid-session (such as adding a 3-way conference). 8

9. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Protocol Methods REGISTER – registration of caller on a SIP Proxy server INVITE – starts communication about scheduled relation ACK – start of new relation CANCEL – interrupt of initialization before its actual start BYE – ends relation OPTIONS – ask for attributes of call participants 9

10. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP connection flow 10

11. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP error codes 1xx – initiating , step continuing OK but it hasn’t finished yet 2xx – success , step has been finished without issues 3xx – redirect , step is in progress but it’s awaiting some data 4xx – client error , request failed, server can’t process it 5xx – server error , client request OK, server problem 6xx – fatal error , completely fatal error can’t be processed. 11

12. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Good to know about SIP Purely text based (easy to debug and get error codes!) Can run over IPv4 and IPv6 Can use both TCP or UDP (very likely IPv4 over UDP) SIP devices can talk to each other directly (but proxy is 99%) SIP proxy deals only with “messaging”. Doesn’t transfer call. SIP proxy makes client implementation easier (translation of extension into SIP address – IP + location and type of device). Proxy CAN provide mid-call features: conferencing, accounting SIP dos NOT do call control features – voice mail, auto-attendant. This is feature of end-points. 12

13. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. After SIP deployment Woaa ! I made a SIP call and before an hour I didn’t even know I can do it from my network! 13

14. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Typical SIP problems after deployment Poor audio quality or user cant’ connect Interoperability – various vendors problem. Basic connection Codec Negotiation – codec support by end-points Slow Error Recovery – UDP effect No Conference control – has to have SIP server/PBX Others: Echo on call, Registration is dropping, Timeouts Incoming call doesn’t hear you Incorrect server settings, Wrong username/password DNS and network issues – check your routers accessibility Firewall – SIP ALG rules, ISP issues 14

15. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Troubleshooting - connection SIP connection and RTP – use Wireshark (use VoIP Calls view) Various reasons – format of options, codec issue. But it’s easy to read. 15

16. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Troubleshooting - quality Focus on RTP data (example with wireshark ) Get the codec used Select “RTP-Stream analysis” from Wireshark menu. Check Jitter, packet loss. Eliminate network issue vs. hardware. 16

17. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Call reconstruction – Wireskark in action 17

18. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Trunking is what companies care about 18

19. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Trunking – what it is? Using SIP for delivery Unified Communication services to the customer (voice, video, desktop sharing, etc.) VoIP over “shared” wire Save $$$ comparing to PSTN telephony. Easy switch – keep your PBX 19

20. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. 3 Typical problems Trunks dropping intermittently is a provider problem. If it happens consistently, check with the provider first before approaching the IP PBX or SBC vendors . One-way audio is most likely a configuration issue, poor data entry, or just plain negligence. It could be a misconfiguration in the IP PBX, SBC, or at the trunk provider . Poor voice quality created by latency, jitter or packet loss may be the result of not enough trunk bandwidth being allocated. These are three less likely issues: Codec mismatch is a configuration problem that can occur in the IP PBX, SBC or at the provider’s site. Trunk registration failures are a provider support issue. No audio is probably another configuration issue. It can be in the IP PBX, SBC or at the provider site. The least common issues are: ITSP SIP server failures are the provider’s responsibility to prevent. Incoming call transfer failure is another provider responsibility to ensure works properly. Call conferencing with an external caller failing is another provider responsibility to resolve. 20

21. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Trunking problems (survey 850 WW resp.) 21

22. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. Example of failures Use 'debug ccsip messages '. (leverage CUBE to do it) Session protocol UDP. INVITE from CUCM, No Offer SDP in INVITE. It means Delayed Offer, in case of Early Offer SDP is included in INVITE . Delayed Offer. Offer SDP in 200 from remote site. Answer SDP in the following ACK from CUCM 22

23. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP Trunk Monitoring Identify top failures mentioned above. Volume of calls per SIP trunk in a time (spikes). Pair the call with the SIP trunk ID – for provider reference. 23 # of Phones SIP Trunks Needed 2 4 5 6 10 6 25 12 50 23 100 30

24. © 2012 SOLARWINDS WORLDWIDE, LLC.  ALL RIGHTS RESERVED. SIP & how to do it? Q & A 24