Evolution of Avaya Telephony Solution

Avaya DEFINITY Telephony System
Avaya DEFINITY portfolios are Avaya’s Pure TDM Telephony products in the form of cabinet with one or several carriers which consists of several slots for different type of Hardware Cards. Both Control Messages (CCMS) and Bearer traffic are all transported in TDM channels. Besides, all Hardware Cards in one cabinet, regardless of which carrier they reside, are interconnected by high-speed TDM BUS in the backplane of the cabinet. In the scenario of cabinet cascading, cabinets are interconnected by TDM cascading cables which basically act as the TDM BUS in the backplane. For the deployment spanning a long distance, several cabinet can be inter-networked by Inherent CSS fiber switch or external ATM fiber switch which are called Center Stage PNC and ATM PNC respectively.
Avaya DEFINITY Architecture

SPE(Switch Processing Element): the core for the whole DEFINITY Telephony system, CPU resource for Dial Plan, Call Routing.
TDM BUS: Circuit Switch based Matrix for control&management messages, signaling & voice bearer traffic exchanging.
Port Network (PN)
: it is actually just a unit of call processing resource used in Avaya DEFINITY System. Physically, it could be one or a group of cascaded cabinets with TDM BUS of up to 512 timeslots (484 for call processing, 28 for management and maintenance).PNPNC(Port Network Connectivity): enable interconnecting different PNs, fall into 2 categories (inherent CSS or ATM Fiber Switch)
CSS(Center Switch Stage): G3r embedded fiber switch used to interconnect PNs.

Avaya Telephony Evolution
The Avaya Telephony System evolves with below footprints:
1. Avaya Traditional DEFINITY: Pure TDM based system with SPE for call processing and routing, PN for terminal & PSTN access, Fiber-Switch Based PNC to interconnect different PNs.
2. IP-Enabled DEFINITY: C-LAN & MediaProcess Cards are introduced to enable VoIP, mainly H323 IP Phone.
3. Multi-Connect Telephony: previous SPE is replaced by S87xx servers + IPSI, which considerably empowers call processing and routing function element in order to support large-scale deployment in the future.
4. IP-Connect Telephony: Traditional PN-SCC or PN-MCC phased out and are replaced by G650/G600. It is actually a transitional architecture on the way of heading pure IP-Based telephony.
Avaya Telephony Evolution

IP-Connect Telephony to Avaya Aura Architecture
1. Further Evolving by introducing PE+h248 GWs: After SCC/MCC replaced by G650/G600, PE(Process Ethernet) is introduced in Media Server to directly take over the H248/H323 Registration & Signaling processing which is normally done by C-LAN card on G650/G600. That is a further forward step to Pure IP based IP Telephony and it also indicates the phasing out of  G650/G600(transitional products) in the future.
Further EvolveThe New Generation GWs(G700/G450/G350 etc) are totally different from PN Gateways such as G650/PN-SCC/PN-MCC. G7xx/G4xx/G3xx GWs, which are quite similar to cisco’s ISR, provides functions ranging from Routing&Switch, Voice, Security etc with Media Module(MM) Cards installed, while PN Gateways use TNxxxx Card. What is more, software-based SLS and hardware-based LSP can be enabled on those remote gateways in case of occasions when gateway loss connection to Main Avaya Media Servers such as S87xx. Here is the capacity planning for reference:
Capacity Planning2. Avaya Aura Architecture for Cloud-based Unified Communication: to be continue

To be continue.