TDC 461 Basic Communications Systems Class #4 24 April, 2001

Agenda Computer Telephony Integration (CTI) Cordless Telephones Cellular Telephones Satellite Systems

Announcements: Midterm exam next week –You can bring one 8.5”x11” sheet of Exam will be multiple choice, true false, fill-in-the-blank, and short answer. You will have to diagram a solution to at least one problem, so be prepared. –Exam will last until 7:30pm. –Review guide on the web.

Computer Telephony Integration (CTI) The concept: –Integrate PBX with computer services to –Integrate voice cabling with data cabling to save money

Why CTI?

PBX System Layout

LAN System Layout

Shared Cabling Voice Network Layout and Data Network Layout looks the same!!

Non-Integrated PBX & LAN

Voice/Data Adjunct Services (with no PBX modifications) Some voice/data convergence can be accomplished without PBX changes. LAN servers can connect to PBX by standard voice trunks. Examples

Unified Messaging Users utilize a single desktop application to receive and send Voice mail can be recorded/heard through PBX telephone set or PC microphone/speaker.

Unified Messaging

FAX Server

CTI Configuration First Party Control – Third Party Control –

CTI First-Party Control Individual connections to desktops

CTI Third-Party Control Connect through CT Server

CTI Third-Party Control Alternative: Direct LAN Connection to PBX

CTI Applications Intelligent Call Assignment for ACD Data lookups triggered by calling number (ANI / DNIS) Linking database records and PBX call records Intelligent Voice Response Unit / Faxback Control voice calls via PC applications

CTI Software Configuration CTI Software required on: – All CTI functions and messaging defined by CTI Applications Programming Interface (API)

CTI APIs Telephony Services API (TSAPI) – Telephony API (TAPI) – CallPath – Java Telephony API (JTAPI) –

CTI Summary Advantages – Disadvantages –. –

Cordless Telephones

 Base unit=>  Portable unit=>  Signaling carried between base and portable using out-of-band frequencies.

Cellular Technologies Cell 1 Cell 2 Cell 3

Previous Wireless Systems Single Powerful Transmitter

Wireless Before Cellular Problem: Limited Capacity Before 1981: –FDM –Limited number of users: –Very limited capacity

Cellular Services 728 Mobile Service Areas (MSAs) defined by the FCC in the United States. 2 Cellular carriers in each MSA –A Carrier : –B Carrier :

Cellular Concept: Many Low Power Base Stations Cell 1 Cell 2 Cell 3

Cellular increases capacity using Frequency Reuse 7-way Frequency Reuse: – Chan Chan Chan Chan Chan Chan 1-40 Chan Chan 1-40 Chan Chan Chan Chan

Mobile Telephone Switching Office (MTSO) Interconnection=> Switching=>. Interconnection with wireline=> MTSO CentralOffice Mobile Office Trunks

Cellular Network Signaling Registration – Call Handoff – Roaming –

Call Handoff Caller moves from one cell to another:

Cellular Systems Advanced Mobile Phone System (AMPS) IS-54B Digital Cellular (TDMA)

Personal Communications Systems (PCS) Combines voice and data services Intelligent network Code Division Multiple Access (CDMA)

Personal Communications Systems (PCS) Smart PCS equipment=>

How to Share Airwaves? Frequency Division Multiple Access (FDMA) –

How to Share Airwaves? Time Division Multiple Access (TDMA) – –Example: For 3 voice channels, Voice Channel 1: data bytes #1, #4, #7, #10, … Voice Channel 2: data bytes #2, #5, #8, #11, … Voice Channel 3: data bytes #3, #6, #9, #12,...

How to Share Airwaves? Code Division Multiple Access (CDMA) – –Example: Voice channel 1: ‘0’ = , ‘1’ = Voice channel 2: ‘0’ = , ‘1’ =

How to Share Airwaves? Advantages: –FDMA: –TDMA: –CDMA:

Satellite Systems

Satellites are big repeaters in the sky

Advantages to Satellites Coverage –Geosynchronous satellite=> Distance Insensitivity – Scalability –

Disadvantages to Satellites Propagation Delay – Weather –

Satellite Orbits Geosynchronous Earth Orbit (GEO) –Orbits 22,300 miles above earth –Appears to be motionless from Earth –Uses: TV, telephony, intelligence Low Earth Orbit (LEO) –Orbits miles above earth –Satellite rises and sets in ~15 minutes when viewed from Earth –Advantage: Much smaller propagation delay –Uses: New voice/data networks

Example: Iridium Iridium is LEO network –Built by consortium lead by Motorola –Constellation of 66 LEO satellites 11 satellites in each of 6 different polar orbits –Provides voice communications from anyplace to anyplace on Earth. –12 Gateways provide interconnection to international public telephone networks –Commercial service started in Nov. 1998