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Q1 What are the basic configuration options for Prosody X?
Prosody X PCI configurations are: 1, 2 or 4 DSPs to manage up to 150 channels of speech, fax and data in either TDM or IP per DSP; and an optional PMXC module with 1, 2, 4 or 8 E1/T1 trunks or PMX module with 4 or 8 trunks.
Prosody X cPCI configurations are: 2, 4 or 8 DSPs; and an optional PMX with 8 or 16 E1/T1 trunks.
See the Prosody media processing CPI (APB0018) and the Prosody X product bulletins (APB0181 and APB0201), which are available from our website or contact your Account Manager for more details.
Q2 What is the difference between PMX and PMXC module types for Prosody X?
The PMX and PMXC are optional modules for Prosody X used to provide connectivity to TDM networks. The difference in the module type is in the signalling protocol coverage. The PMXC module is a superset of PMX, providing additional support for CAS type protocols (like T1 robbed bit) and SS7. If your application uses CAS or SS7, be sure you specify PMXC module a type in your order.
Q3 Is the number of media DSPs a point of sale option for Prosody X?
Yes. The DSP configuration is a point of sale option. Aculab has a policy of testing all the deliverables prior to shipment, using the particular configuration ordered by a customer, to ensure highest quality of all the products. Therefore, additional DSPs cannot be fitted at a later stage.
Q4 Can I add any functions to an existing Prosody X board?
Yes. You can add new or updated algorithms i.e., take advantage of any new software releases, which can be downloaded from our website via the Aculab installation tool (AIT).
Q5 What operating systems are supported by Prosody X?
Aculab supports a number of popular operating systems; Linux, SPARC Solaris and Windows. Please use the following link for more details: http://www.aculab.com/support/ait_telephony_software.asp. If you have additional requirements, please do not hesitate to contact your Account Manager.
Q6 Is Prosody X compatible with other Aculab boards?
Yes. Customers are able to ‘mix and match’ or interoperate products in the same platform. Note that for Prosody X the PCI chassis must be PICMG 2.3 compliant i.e., it must supply +3.3V and +5V. Older PCI boards use only +5V (see technical note APB0140, which is available from your Account Manager, for compatibility information on PCI boards). Prosody X boards can be connected to Prosody and E1/T1 digital network access boards through the H.100 bus on PCI platforms and H.110 on cPCI platforms.
Q7 What are the TDM options for Prosody X boards?
It is widely recognised that the circuit switched network will continue to be a great workhorse for many years to come, with the transition to IP-based transport happening over a period of years. To complement this, Prosody X provides the option of E1/T1 trunk interfaces via daughter boards known as PMX or PMXC modules, to ensure traditional TDM connectivity using the worldwide protocol suite Aculab is renowned for. All CAS, IP and ISDN protocols listed in the latest issue of Aculab’s signalling protocol portfolio (APB0003, Issue 6) will be supported. You may view this on our website at: http://www.aculab.com/products_main/approvals_main.htm
Prosody X PCI can be ordered with 1, 2, 4 or 8 E1/T1 trunks and Prosody X cPCI with 8 or 16 E1/T1 trunks.
Q8 Do Prosody X boards support SS7?
Yes. Aculab’s SS7 protocol stack coverage provides signalling messages for MTP, ISUP, SCCP and TCAP procedures and is constantly being upgraded. Please ensure that you specify a PMXC module type in your order if you plan to use SS7.
Q9 Does Prosody X use the same API as other Aculab boards – will I need to learn a new API?
Prosody X uses the same API for TDM-only applications. However, as should be anticipated, new functionality and capabilities are available with Prosody X – notably for IP telephony – and there are differences at an API level that you will need to accommodate. Nevertheless, the API available to Prosody X users remains consistent with the API for other Aculab boards.
Q10 Are cables supplied with the Prosody X variants that need breakout cables?
Yes. Cables are supplied as part of the product and are included in the price.
Q11 Does each Prosody X board have its own IP address?
Yes. A Prosody X board is always a standalone networked device identified by its IP address. The host MAC, which looks like a NIC to the local host, also has one IP address, and both IP addresses are externally visible.
Q12 Can I have one platform for my application and a remote chassis for a Prosody X board?
Yes. This is one of the benefits of the inherent IP architecture, which is explained in some detail in the white paper titled ‘On-board IP architecture – A new approach to computer telephony board design’ (APB0174), which is available from Aculab’s website or your Account Manager.
Prosody X is a self-contained board that is remotely controlled over Ethernet. In a remote chassis, the Prosody X board boots from on-board flash memory at power-up and gets its configuration and IP address remotely over the Ethernet (it boots in the same way if installed in a local host, but gets configuration and IP address over the PCI bus). There are no drivers or libraries to be downloaded to the remote chassis. Protocol firmware is downloaded to a PMX or PMXC trunk module on the remote board via Ethernet.
Q13 What is the total number of Prosody X boards that can be controlled remotely?
The number is unlimited in theory; very much in the same way that you can connect an unlimited number of devices to the Internet.
Q14 How many Prosody X boards should be able to run in one chassis?
The usual considerations will apply, such as power and cooling requirements and CT bus loading, if used. In addition, the processing power needed to simultaneously drive large numbers of IP and TDM channels in a big system will be an important factor affecting the total number of boards. And your application will need to be written efficiently, of course. The use of PCI bridges has no effect on Prosody X operation.
Q15 Can I manage Prosody X via SNMP?
Yes. Both Net-SNMP and Microsoft’s SNMP are offered to provide choice, and the host-based solution allows one agent to report on multiple boards.
Q16 How do I connect a call from a board in one chassis to a board in another chassis?
If you need to feed audio from a DSP on a board in one chassis to one in another chassis you would use the TiNG API to create an RTP endpoint on each DSP and have one send the audio to the other as RTP over Ethernet. This is exactly the same method as would be used to transfer audio for VoIP calls.
Q17 Do Prosody X boards in separate chassis need to use different point codes for SS7?
No. They can come under the same point code. This is one of the beneficial redundancy/resilience features available with Prosody X that makes its performance with SS7 more attractive to users in the telco space.
Q18 Do I need a PICMG 2.16 compliant chassis to host a Prosody X cPCI board?
No. A 1 Gbit/s PICMG 2.16 Ethernet backplane is the recommended specification, however, the choice of dual redundant 1 Gbit/s Ethernet is available via an optional rear transition module. With PICMG 2.16 there is no Ethernet egress via the rear transition module, which is then only needed for TDM connections – the backplane switching fabric control takes care of Ethernet to the outside world. If a non-PICMG 2.16 chassis is used, the alternative rear transition module provides eight double wired RJ45s for TDM trunk connections and dual RJ45s for Ethernet.
Q19 Can Prosody X be used with voice engines for automatic speech recognition (ASR), text-to-speech (TTS) and speaker verification and identification (SVI) applications? How could it be integrated with 3rd party products working with VoiceXML?
Prosody X developers can use IP media processing resources available on the board in conjunction with voice engines provided by 3rd parties, which are supported using the MRCP protocol. Aculab has tested the Prosody X platform with a wide range of products from "Connected with Aculab" partners; Atlas, Loquendo, Nuance, Vebio and Telisma. Additionally, Prosody X can be used with any other voice engine supporting MRCP v1 or v2, including IBM's WebSphere Voice Server.
Q20 What VoIP applications leverage the strengths of Prosody X?
Prosody X is a very sophisticated and powerful IP media processing platform suitable for a wide range of VoIP and TDM applications. The product is designed to enable the seamless migration from TDM to VoIP-based solutions and provides a wide functionality set in both domains. All solutions designed with Prosody X will benefit from its inherent strengths: high channel count, low cost per channel and scalability beyond a single machine.
Target applications for Prosody X include, but are not limited to:
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Media and signalling gateways |
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IP media servers |
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Contact and call centres |
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IVR servers and voice portals |
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Conference servers |
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Fax bureaux |
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Session border controllers |
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Unified messaging systems |
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Quality of service monitoring and test equipment |
Q21 How reliable is the Prosody X remote control when operated in a highly loaded network with congested traffic?
Prosody X architecture enables the creation of redundant solutions with controlling applications executed not only on the host machine, but also on a remote one. In the latter case, the remote control application establishes 'ownership' of some of the resources available on the Prosody X board. The mechanism implemented for Prosody X enables the establishment of very reliable remote board control, even over highly loaded networks.
Highly loaded networks have congested traffic, which usually leads to significant packet loss. In order to keep appropriate communication between the board and the remote high level application in severe network conditions, Prosody X utilises a special protocol called ASSP (Asymmetric Semi-Stream Protocol), which is implemented over the UDP networking protocol. The protocol maintains a very low latency connection even when encountering packet loss.
Q22 What mechanisms are available on Prosody X to improve audio quality if the IP traffic is congested?
Congested network traffic leads to packet losses. Usually, the RTP stream packets have appropriate ToS (type of service) marking in the packet header to prevent routers from dropping packets of the voice stream and dropping non-real time packets instead. Nevertheless, in a network with a very high load, all the RTP streams will have the same ToS priority and the network routers may start dropping the packets randomly, according to the state of the internal ingress/egress queues. The missing packets of the RTP stream cannot be recreated again and the quality of the received audio will degrade.
Additionally, congested network traffic frequently leads to significant volatility in the RTP stream latency. Prosody X enjoys the benefit of an adaptive jitter buffer to compensate for most cases of the latency variations accruing in LAN and WAN environments. Nevertheless, some extreme latency changes could lead to jitter buffer under/over-run and a part of the voice packets could be lost, resulting in singular or repetitive audio distortion. A user can control the jitter buffer size and parameters using an API command. Most of the modern codecs, such as G.729AB, could cope with moderate packet loss keeping an acceptable level of audio quality.
Q23 Where I can find relevant material to read more about Prosody X architecture?
Aculab has had several articles published in leading industry media, describing the architecture of Prosody X. A good place to start is an article published in VON Magazine (http://www.vonmag-digital.com/vonmag/200512/ (select: Contents - Editorial). Also, please note the Aculab website is always the place to check for the latest information on our products.
Q24 To whom should I pay licencing fees for G.723.1A and G.729AB codecs and how much should I pay?
The intellectual property rights (IPR) for ITU-T G.723.1A and G.729AB codecs belong to a consortium of organisations and are licensed by agent companies. Aculab has the codec available for application development with Prosody X and our customers can access this functionality free of charge. Nevertheless, as soon as the end user applications are taken to be installed and run in the field, the customers have legal responsibility to pay the licence fees to the IPR holders.
Customers have two options to comply with the legal requirement. The first option is to contact agent companies to negotiate the amount to be paid and make the payment to this organisation directly. Although it is the most direct way, Aculab realises that for many customers, having only small or unpredictable amounts of G.723.1A or G.729AB channels in use, this could be expensive, because of the high initial fees. Aculab has therefore decided to provide our customers with a service, which is free of charge, to act as an intermediary and eliminate the need to deal with the agents directly. Accordingly, the second option is to pay your licence fees through Aculab. We will pass your payment to agents on your behalf. This service is designed to help you with the adoption of the new functionality. If you need more clarification you can always contact your Account Manager.
Q25 Is it possible to build mixed protocol drivers for the Prosody X boards with PMX/PMXC trunk modules?
All TDM trunks on PMX or PMXC modules are completely independent resources, therefore selection of E1 or T1 mode, termination impedance and the signalling method can be configured arbitrarily. The flexibility of Prosody X allows using TDM trunks in conjunction with any of the signalling protocol offered by Aculab.
Q26 Do I need to buy a rear transition module (RTM) for Prosody X cPCI separately?
No. The RTM is supplied with all Prosody X cPCI boards and is already included in the product price.
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