VoIP and IP Telephony

Reach Out and Ping Someone

ISAC Spring School 2006

21 March 2006

Anthony Kava, Sr. Network Admin

Pottawattamie County IT

Definition

VoIP – Voice over Internet ProtocolVoice Transport (i.e., trunking)Replacement for Traditional Circuits

IP TelephonyInternet Protocol for Telephone Applications

PC <-> PCPC <-> PhonePhone <-> Phone

Sometimes Interchangeable

Applications

Remote OfficesRoad WarriorsMessaging IntegrationNetwork ConvergenceToll BypassPBX ReplacementAdd-on to PBX

Benefits

Open ArchitectureInteroperabilitySingle NetworkUniformityReduced MaintenanceEnd-user MobilityResilient IP Network

Caveats

Infrastructure CostsElectrical PowerNew TechnologyComplexityReliabilityEmergency ServicesSecurity

Switching Comparison

Circuit-switchedEnd-to-end ChannelOpen for Call Duration Dedicated Bandwidth

Packet-switchedVoice Split into Data PacketsAsynchronous DeliveryShared Bandwidth

Network Considerations

BandwidthCODECs

G.711 μLaw / αLaw (64 Kbps)G.729 (8 Kbps)GSM (13 Kbps)

LatencyAcceptable Delay

PSTN (45 ms)Link + Encoding Delay

JitterBufferingDelaysDrops

CODEC Comparison

303.655.3G.723.1 ACELP

303.96.3G.723.1 MP-MLQ

103.78G.729a CS-ACELP

102.688G.729 x 3 Encodings

103.278G.729 x 2 Encodings

103.928G.729 CS-ACELP

3 to 53.6116G.728 LD-CELP

13.8532G.726 ADPCM

0.754.164G.711 PCM

Compression Delay (ms)MOS ScoreBit Rate (kbps)Compression Method

Source: http://www.cisco.com/warp/public/788/voip/codec_complexity.html

A Very, Very Brief History

1876 – “Mr. Watson, come here, I want you!”1973 – Network Voice Protocol (NVP)

ARPA Network Secure Communications (NSC) ProgramSecure, High-Quality, Low-Bandwidth, Real-time, Full-Duplex

1981 – Voice FunnelStreaming Audio/Video over Packet-switchingUsed for Video Conferencing over ARPANET during the 1980s

1999 – Cisco Introduces Their First IP Phone

IP Telephony ProtocolsH.323 – ITU Multimedia Standard

Video ConferencingGateway DevicesGatekeeperMost Widely DeployedBased on ISDN Q.931

Session Initiated Protocol (SIP)Leading VoIP Signaling ProtocolReal-time Transport Protocol (RTP)Superset of PSTN FeaturesText-based Protocol (like HTTP)

Cisco Skinny Client Control Protocol (SCCP)Proprietary Protocol Used by Cisco Call Manager

Inter-Asterisk eXchange (IAX)Used by Asterisk Open-source PBXTrunking Over Single UDP Data Stream

Media Gateway Control Protocol (MGCP)Call AgentMedia GatewaySignaling Gateway

Example SIP MessageSIP/2.0 100 TryingVia: SIP/2.0/UDP 10.x.x.x:5060;branch=z9kG4bS690421ddFrom: "Tony Kava" <sip:7123284735@10.x.x.x>;tag=am213z2vf3To: <sip:93428463@10.x.x.x>;tag=44E9C180-556Date: Mon, 20 Mar 2006 03:23:12 GMTCall-ID: 623528306fd625411b6e82ea6b711ab7@10.x.x.xServer: Cisco-SIPGateway/IOS-12.xCSeq: 102 INVITEAllow-Events: telephone-eventContent-Length: 0

Text-based ProtocolThree-digit Codes like HTTPHeaders like SMTPEasy to Troubleshoot with Protocol Analyzer

SIP IP Phone Manufacturers

CiscoD-LinkGrandstreamLinksysPolycomSnomUnidenZultys

SIP Infrastructure / Demo

SIP ProxyAsterisk PBX

Soft PhoneX-Lite

Hard PhonePolycom IP 501

IP Telephony at PottCounty

IP Telephone TestBegan January 200517 x Cisco 7960 PhonesIT, EMA and PlanningAsterisk PBXDell PowerEdge 1750Rolm 9751Cisco 3825 RouterCisco 6509 CoresCisco 3550 Switches

Cisco 7960GIP Phone

Cisco 3550-24PWR

Cisco 6509 Core

Cisco 7960GIP Phone

Cisco 3550-24PWR

Cisco 3825

PSTN

Rolm 9751

Asterisk

IP Telephony at PottCounty

IP Telephone TestThe Good

Positive User FeedbackMinimal DowntimeSurvived EMA Exercise

The BadRouter Memory Leak BugShared Line AppearancesOccassional Echo

Cisco 7960GIP Phone

Cisco 3550-24PWR

Cisco 6509 Core

Cisco 7960GIP Phone

Cisco 3550-24PWR

Cisco 3825

PSTN

Rolm 9751

Asterisk

IP Telephony at PottCountyAsterisk PBX

Remote IP PhoneSoft Phone via VPNEasy to Create MenusCall Queue CapabilityAsterisk Gateway Interface (AGI)Helpful Apps

Ten Digit DialingAnyWho Reverse LookupBusiness Hours LogicIdentification ExtensionText-to-Speech (Festival)

[jailmenu]exten => s,1,Answerexten => s,2,DigitTimeout,5exten => s,3,ResponseTimeout,15exten => s,4,Background,jailmenu

exten => t,1,Playback,vm-goodbyeexten => t,2,Wait,1exten => t,3,Hangup

exten => i,1,Playback,pbx-invalidexten => i,2,Goto,s|3

; 1 - Information submenuexten => 1,1,Goto(jailsub1,s,1)

; 2 - Jail Administration Office (submenu)exten => 2,1,Goto(jailsub3,s,1)

; 3 - Sheriff's Office 2200exten => 3,1,Dial(SIP/2200@10.x.x.x,60)

VoIP / Convergence at PottCounty

PCSO: BeforeRolm 9751 SwitchT1 Split for Data / Voice

12 Channels Voice768K Data (12 Chan.)

Single Data ApplicationVideo Over ISDN Lines$285 (T1) + $500 (ISDN) = $785 / month

3 x ISDN3 x ISDN

T1

Cisco 2501

PCSO LAN

Multiplexer

Rolm 9751

MultiplexerCisco 2501

Rolm 9751

AS/400 LAN

PSTN

Polycom Video Polycom Video

VoIP / Convergence at PottCounty

PCSO: AfterRolm 9751 Switch12 VoIP Channels2 x T1 as IP Link (3 Mbps)LANs InterconnectedVideo Over IP with H323$285 (T1) + $285 (T1)= $570 / month ($215 less)

T1

T1

Cisco 2811

PCSO LAN

Rolm 9751

Cisco 3825

Rolm 9751

County LAN

Polycom Video Polycom Video

Any leftover questions?

ISAC Spring School 2006

21 March 2006

Anthony Kava, Sr. Network Admin

Pottawattamie County IT