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Aastra OpenCom 510 User Guide - Page 119

Latency and Packet Length, c. 6.3 kilobit/s

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Voice over IP (VoIP) Fundamentals A modern Intranet normally offers enough performance reserves and reliability to make good-quality VoIP telephony possible. Specific components can also be optimised; for example by using a modern switch which evaluates the TOS byte of IP packets or by replacing unreliable connections. 11.1.2 Latency and Packet Length For technical reasons, there is always a delay ("latency") between the recording of voice data via the microphone and playback via the receiver. Voice data is recorded for a short period so that it can be sent in an IP packet. The IP packet also has a signal-propagation delay before the receiver can begin playback. For these reasons, the extra time required for voice-data encoding and decoding may be neglected. An IP packet consists of protocol data and user data. Sending shorter voice-data packets causes the ratio between the user data and the protocol data to become unfavourable and increases the bandwidth required. Sending longer voice-data packets increases latency. The length of the voice-data packets must therefore be adjusted to the requirements of the transmission medium. Shorter voice-data packets can be sent if a direct ethernet connection exists. If an 64 kilobit/s ISDN line is to be used for transmission, then longer voice-data packets should be used. Longer voice data packages are generally used for SIP telephony over the Internet. The following table provides an overview of the required bandwidth for a telephone connection with various parameter settings. The values apply to halfduplex ethernet; for full-duplex the values can be halved. Required bandwidth (kilobit/s) with respect to Packet Length and Codec Packet G.711 (not G.729A G.723.1 G.723.1 Length (ms) compressed) c. 6.3 kilobit/s 6.3 kilobit/s 5.3 kilobit/s 20 180.8 68.8 30 51.2 48.0 45.9 40 42.4 50 37.12 117

Section	Page
OpenCom 510	1
Mounting and Commissioning	1
Contents	3
1. Features	11
2. Factory Settings	16
2.1 Telephony Functions	16
2.2 Authorisations	16
2.3 Internet Functions	19
3. Preliminary Information	21
3.1 Construction of the OpenCom 510	21
3.2 Scope of Delivery	21
3.3 Declarations of Conformity	22
4. Installation	23
4.1 Safety Precautions	23
4.1.1 General Instructions	23
4.1.2 Notes on the Mains Supply	24
4.1.3 Notes on EMC and Earthing	24
4.1.4 Notes on Installing the OpenCom 510	25
4.1.5 Notes on Installing Terminals	26
4.2 Installation, Ambient Conditions	26
4.3 Installation in a 19\	27
4.4 Installing Modules	28
4.4.1 Slots	29
4.4.2 Notes on Disconnecting the Mains Supply	30
4.4.3 Installing the Central Control Module	31
4.4.4 Installing Interface Cards	33
4.4.5 Installing a Power Supply Unit	35
4.5 Backplane	36
4.6 Uninterruptible Power Supply	39
4.7 Power Failure	39
5. Interfaces and Connectible Terminals	41
5.1 Overview	41
5.2 S0 Ports	42
5.2.1 Termination	43
5.2.2 External ISDN Ports (S0 External)	45
5.2.3 Internal S0 Ports	46
5.3 Upn Ports	46
5.3.1 Terminals Connected to Upn Ports	46
5.3.2 Technical Information	47
5.3.3 DECT Base Station Connection Variants	48
5.4 a/b Ports	50
5.4.1 Terminals Connected to a/b Ports	50
5.4.2 Technical Information	52
5.5 LAN Port	53
5.5.1 DSL Port	53
5.5.2 Service PC	54
5.6 COM Port	54
6. Accessories and Adapters (OpenPhone 61, 63, 65)	56
6.1 Upn Adapter	56
6.2 a/b Adapter	56
6.3 Audio Adapter	57
6.4 Approved Devices / Approved Accessories	58
6.5 Device Combinations	59
7. Extensions and accessories for system telephones (OpenPhone 71, 73, 75)	63
7.1 Power supply unit	63
7.2 Keypad extensions	64
7.3 Headset	66
8. Modules	67
8.1 Module Naming Conventions	68
8.2 Overview of Available Modules	69
8.3 MPS+1-AC	71
8.4 MC+1-3	74
8.5 MT+S2M1-1	78
8.6 MX+S01-8	82
8.7 MS+UPN1-8	85
8.8 MS+UPN2-8	87
8.9 MS+A1-8	89
8.10 MS+A1-4	91
9. Configuration	93
9.1 Brief Guide to Initial Configuration	94
9.2 Configuring the OpenCom 510	96
9.2.1 Preparing the Configuration	96
9.2.2 Starting the Web Console	96
9.2.3 Loading the Online Help	98
9.2.4 Finishing the Configuration	98
9.2.5 Preconfiguration	98
9.2.6 Offline Configurator	99
9.2.7 Remote Configuration	99
9.2.8 Codes for IP Configuration	101
9.2.9 Saving and Loading the Configuration	102
9.2.10 Receiving System Messages as E-Mail	102
9.2.11 Loading SW Updates	103
9.2.12 Resetting the System Data	103
9.2.13 Generating Your Own MoH Files	104
10. Configuration Examples	105
10.1 OpenCom 510 in Computer Networks	105
10.2 Introduction to TCP/IP	106
10.3 OpenCom 510 in a Serverless LAN	107
10.3.1 DNS Name Resolution	108
10.3.2 Internet Access	108
10.3.3 RAS Access	109
10.4 OpenCom 510 in a LAN with an IP-enabled Server	110
10.4.1 DNS Name Resolution	110
10.4.2 Internet Access	111
10.4.3 RAS Access	112
10.5 Branch Link	113
10.6 Useful Information on Internet Access	114
10.6.1 Costs	114
10.6.2 Using the Web	114
10.6.3 E-mail	115
10.6.4 NAT	115
11. Voice over IP (VoIP)	117
11.1 Fundamentals	118
11.1.1 Propagation Delay and Bandwidth	118
11.1.2 Latency and Packet Length	119
11.1.3 Voice Quality	120
11.1.4 Optimisation	122
11.1.5 Call set-up	122
11.1.6 Useful services	123
11.2 Media Gateway (MGW)	123
11.2.1 MG+ETH1-1	124
11.3 SIP Telephony	126
11.4 VoIP System Telephones	128
11.4.1 Device Properties	128
11.4.2 VoIP System Telephone Configuration	129
11.4.3 LAN DHCP Server	130
11.4.4 Start Procedure	131
11.5 OpenPhone IPC	133
11.5.1 Installation	134
11.5.2 Configuration	134
12. DECTnetIP	136
12.1 Properties	136
12.1.1 DECT base stations	136
12.1.2 Features	137
12.2 Configuration	138
12.2.1 Dual operation	139
12.2.2 Synchronisation	139
12.2.3 Setting up the WLAN function	140
12.2.4 Configuring for a remote location	143
13. PBX Cascading	147
13.1 Variants of PBX Cascading	147
13.2 Functionality of PBX Cascading	147
13.3 Putting a Cascaded PBX into Operation	148
13.3.1 Notes	151
13.4 Licensing Information	152
14. PBX Networking	153
14.1 Connections	154
14.1.1 Protocol: Q.SIG or DSS1	154
14.1.2 Master/Slave	155
14.1.3 L1 Clock	155
14.2 Types of Point-to-Point Connections	156
14.2.1 Direct Connection	156
14.2.2 Connection via an Active Transmission System	157
14.2.3 Connection via the Public Network	157
14.2.4 Connection via Q.SIG.IP	158
14.3 Configuration	159
14.3.1 Trunk groups	159
14.3.2 Routes	159
14.3.3 Numbering	160
14.4 Technical Details	162
15. Team Functions	163
15.1 Introduction	163
15.1.1 Explanation of Keys	163
15.1.2 Team Configuration	165
15.2 Examples of Use	166
15.2.1 Executive/Secretary Team	166
15.2.2 Three-member Team	168
15.2.3 Unified Team	169
15.2.4 Toggle Team	170
16. Call Queue	173
16.1 Introduction	173
16.1.1 Activation of Queues	174
16.1.2 Call Forwarding	174
16.1.3 Pickup	175
16.1.4 Hunt Groups	175
16.2 Examples of Use	175
16.2.1 Enquiry Station for an Operator with Two System Telephones	175
16.2.2 Group of Three Enquiry Stations	177
17. Multi-Company Variant	179
17.1 Configuring the Multi-Company Variant	180
17.1.1 Activating the Multi-Company Variant	180
17.1.2 Configuring and Managing Companies	181
17.1.3 Assigning Users	181
17.1.4 Assigning Trunk Groups/SIP Accounts	182
17.1.5 Allocating Routing Codes	182
17.1.6 Configuring the Company Exchange	183
17.2 Working with the Multi-Company Variant	183
17.2.1 Company Telephone Book	183
17.2.2 Making Calls Between Companies	184
17.2.3 Billing Charges per Company	184
18. Configuring the PC Software	185
18.1 PC Offline Configuration	185
18.2 Setting up TAPI	187
18.3 Setting up NET CAPI	189
18.4 Using the Systray Display	190
18.5 Browser for OpenCTI and OpenHotel	191
18.6 Setting up Video Telephony	192
18.7 Synchronising the PC Clock	193
18.8 Address Queries using LDAP	194
19. Configuration Guide	196
19.1 Overview	197
19.2 PBX Ports	198
19.3 LAN	199
19.4 WAN Settings	200
19.5 RAS Settings	201
19.6 Branch Settings	202
19.7 E-mail Function	203
19.8 E-mail Access	204
20. Frequently Asked Questions	205
20.1 General/Hardware	205
20.2 Telephony	206
20.3 DECT	208
20.4 LAN	209
20.5 Internet	210
21. Technical Data	213
22. Notes on disposal	216