1. 1 IEX8175 RF Electronics Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst. avo.ots@ttu.ee

2. 2 Evolution “amazing – the phone rings” “does it do call transfer?” “how can I make it stop ringing?” 1996-2000 2000-20032004- catching up with the digital PBX long-distance calling, ca. 1930 going beyond the black phone

3. Open Telephony TDM/ Circuit Switch Digital Trunk Subsystem Subsystem LineConcentrationLineConcentration AdministrationMaintenanceBillingAdministrationMaintenanceBilling Call Control Connection Control Features Call Control Connection Control Features Common Channel Signaling Complex Common Channel Signaling Complex Switching Network Standards-Based Packet Infrastructure Layer (IP, ATM) Standards-Based Packet Infrastructure Layer (IP, ATM) Open Call Control Layer (SIP, H.323, MGCP, etc.) Open Call Control Layer (SIP, H.323, MGCP, etc.) Open Service Application Layer (JAIN, AIN, TAPI, JTAPI, XML etc.) Open Service Application Layer (JAIN, AIN, TAPI, JTAPI, XML etc.) Open/Standard Interface Brian Gracely, Cisco, 2001

4. 4 Channel Sharing Channel Sharing Techniques Static Channelization Dynamic Medium Access Control Scheduling Random Access

5. 5 VoIP Codecs

6. 6 Voice Packet Codec G.729A (ITU – T)) 20 ms, => Payload 20 octets Ethernet+FCS+Preamble:26 bytes 802.1q VLAN Tagging 4 bytes IP: 20 bytes UDP: 8 bytes RTP:12 bytes Voice Payload:20 bytes ---------- 90 bytes

7. 7 Overhead/payload

8. 8 Q o S

9. 9 Links http://www.ietf.org/rfc/rfc0791.txt?number=791 http://www.ietf.org/rfc/rfc0793.txt?number=793 http://www.packetizer.com/ http://en.wikipedia.org/wiki/VoIP