Vega Gateway Scenarios A Pre-sales Engineer’s guide This guide has been written to assist the pre-sales engineers of VegaStream’s distributors and their resellers. The guide details a set of standard configurations along with key considerations and recommended 3rd party interoperable products. A guide to the scenarios and information you will find within this document are listed below. 1. 2. 3. 4. 5. 6. 7. 8. 9.
1. VoIP between sites Aim: To reduce inter-site call costs without changing the user experience Many multi-site companies find that staff making calls between sites is a significant company expense. Finding a method of reducing to zero the ongoing costs of these calls would be a real benefit to the bottom line. By inserting a Vega gateway between the PSTN and the PBX the Vega gateway can groom calls that are destined for other site(s) onto the IP network.
Telephony Network • E1 Euro ISDN signalling is supported by Vega 400 and Vega 100 • T1 NI1 & NI2 signalling is supported by Vega 400 and Vega 100 • T1 Loop start, Ground start and Wink start CAS signalling is supported by Vega 400 and Vega 100 • BRI Euro ISDN signalling is supported by Vega 50 BRI • Analog connection is possible, but is not preferred (for details on analog connectivity see later section) IP Network • Recommend – private IP network between sites • Can be any reliable IP connection, including
Future extensions • Add home-workers • Extend the “on net” group to a group of companies who regularly call each other so all calls between these companies are free • Connection to an ITSP for cheaper off-net calls – and possibly for more flexible ingress of national, international or non-geographic numbers. • If PSTN connectivity is not reliable at any site then VoIP can be used as a backup to route outbound calls via a different site.
2. VoIP between sites and home-worker / remote office Aim: To reduce inter-site call costs without changing the user experience, and adding in basic home-worker support Many multi-site companies find that staff making calls between sites is a significant company expense. Finding a method of reducing to zero the ongoing costs of these calls would be a real benefit to the bottom line.
Telephony Network - For PBXs • E1 Euro ISDN signalling is supported by Vega 400 and Vega 100 • T1 NI1 & NI2 signalling is supported by Vega 400 and Vega 100 • T1 Loop start, Ground start and Wink start CAS signalling is supported by Vega 400 and Vega 100 • BRI Euro ISDN signalling is supported by Vega 50 BRI • Analog connection is possible, but is not preferred (for details on analog connectivity see later section) - For home-workers • Analog FXS gateway to connect to analog phone • Optional FXO port to all
When the Vega receives a call from the PBX to that phone number it will groom the call off and forward it to the home-user. USPs • Vega dial planner capability provides powerful routing decision making. For example, calls can be routed based on dialled number prefixes, full numbers, and even on who is making the call.
3. VoIP between sites and home-worker / remote office using a proxy Aim: To reduce inter-site call costs without changing the user experience, and adding in more advanced home-worker support Many multi-site companies find that staff making calls between sites is a significant company expense. Finding a method of reducing to zero the ongoing costs of these calls would be a real benefit to the bottom line.
This configuration can form a good starting point for migrating to VoIP without immediately losing the existing telecoms infrastructure. The Vega can be configured to either route specific telephone numbers to the SIP proxy – where only a small set of numbers is to be handled by the VoIP system, or all calls can be forwarded to the Proxy for it to decide how all calls should be routed. Use of a Proxy can also assist in NAT and firewall traversal.
- For home users who are routed via the proxy • Home-workers will be able to dial extension numbers of any of the PBXs (as the proxy will resolve the phone number and route the call to the appropriate Vega gateway). Calls made to users on a PBX will appear to the PBX to come from the PSTN and so will not provide the advanced functionality to the home-worker that an extension user would have (e.g. voice mail, call transfer, conferencing).
• • • • • • Program in fixed number length dial plans where possible to avoid the DTMF timeout delays incurred when routing calls to variable length numbers Call transfer from PBX to PBX will only work if call transfer PBX to PBX worked across the PSTN (the PBX may block this).
4. Analog long line extensions Aim: To allow 1 or more remote sites / home-workers to have extensions on a centralised PBX, retaining all the PBX’s analog phone functionality When expanding into new offices it can be expensive and inconvenient to set up a new PBX or run analog leased lines from the main site to the new remote site. Data infrastructure between sites however is essential.
IP Network • Recommend – private IP network between sites • Can be any reliable IP connection, including leased line, line of site laser / wireless connection and satellite • QOS should be implemented to ensure that VoIP packets pass through the network in a consistent and timely manner and are not discarded by congested routers • Consider VPN between sites as this: - removes any issues with firewalls / NAT - encrypts audio and management data • For inter-site operation the Internet can be used, but content
5. IP Telephony Aim: To gain additional features available through use of VoIP technology VoIP offers users many facilities and many features currently not known with PBX telephony solutions. Much of the functionality offered by VoIP is controlled through access to the proxy / gatekeeper / media server using a web browser on a PC. Both IP phones and analog phones (via an analog VoIP gateway) may be used to provide telephone access to the users.
IP Network • Recommend – private IP network between sites • Can be any reliable IP connection, including leased line, line of site laser / wireless connection and satellite • QOS should be implemented to ensure that VoIP packets pass through the network in a consistent and timely manner and are not discarded by congested routers • Consider VPN between sites as this: - removes any issues with firewalls / NAT - encrypts audio and management data • A VPN can be used from the home user to the company LAN.
6.
USPs • Vega gateways have been shown to have fast call set-up times and increased call hold times compared to other manufacturers’ gateways due to the quality of the connected call. Considerations • Use of analog gateways to break into / break out of the PSTN may have timing issues over start and end of calls unless line current reversal analog signalling is used. Future extensions • Expansion to a wider range of destination countries and cities through use of ITSP connectivity.
7. TDM to / from VoIP converter Aim: To allow existing manufacturers of TDM based equipment (switches / IVR systems etc) to have a VoIP offering. Many manufacturers of TDM equipment are being asked by customers about their policy on VoIP. Other customers are more demanding and informing suppliers that a migration path to VoIP is essential. It is expensive to integrate a full VoIP solution into a product ‘just because a customer has asked’.
Considerations • Not all supplementary services supported in ISDN signalling directly map to VoIP protocols. If supplementary service are needed it is important to check that they will map OK. Future extensions • 3rd party product choices • - Version 2.1 Vega Gateway Scenarios. 16 March 2006 Page 19 of 33 ©2005-2006 VegaStream Ltd.
8. Leased line eliminator for QSIG connections between sites Aim: To save leased line call costs between sites In larger companies, the PBXs on multiple sites may be linked together via leased lines and using QSIG signalling in order to make the distributed PBXs function as though they were a single PBX. When linking PBXs together in this way, point-to-point connections are required between each and every PBX. This becomes expensive in terms of leased lines.
• • Consider VPN between sites as this: - removes any issues with firewalls / NAT - encrypts audio and management data Vega gateways use the ECMA 333 standard for tunnelling QSIG User experience • There is no change to the existing user experience. The information provided between PBXs is identical, so the PBXs see no change at all. • The user experience is defined only by the PBX capabilities.
9. Analog connections Where PBXs or incoming lines are analog rather than PRI or BRI, Voice over IP can still be used. Care must be taken however, because unlike the symmetrical operation of digital interfaces – where any information provided by one digital telephony device to the other digital telephony device can also be passed in the opposite direction, analog signalling is not symmetric. The two different ends of an analog line are called FXS and FXO.
• • Hook-flash (also known as recall) can be generated by Vega 50 FXO (not SPA-2000) in order to request the attached FXS to switch to command mode (e.g. to initiate a call transfer on a PBX extension port) To clear a call the FXO goes ‘on-hook’ – actually it breaks the circuit that was made when the device went ‘off-hook’ The key thing to note is: FXS devices can receive dialled number information but cannot provide it and FXO devices can generate dialled number information but cannot receive it.
9.b Analog breakout to the PSTN – e.g. for a company or for a PSTN toll bypass A Vega FXO can be connected directly to PSTN lines. Calls from VoIP into the PSTN specify the desired destination number by sending DTMF tones into the PSTN.
9.c FXS connection to a PBX Considerations • Out-dialled calls from the PBX can pass a dialled number to the Vega; it can use this to decide which destination VoIP gateway to route the call to (i.e. multiple destination gateways may be supported), and also which destination end-point to route the call to.
9.e PBX to PBX connectivity – using both FXS and FXO In this configuration calls may be routed PBX to FXS to FXO to PBX or PBX to FXO to FXS to PBX. Calls FXS to FXO Outdialled calls from the PBX can pass a dialled number to the Vega; it can use this to decide which destination VoIP gateway to route the call to (i.e. multiple destination gateways may be supported), and also which destination end-number to route the call to.
9.f PBX to PBX connectivity – using FXS only Out-dialled calls from the PBX can pass a dialled number to the Vega; it can use this to decide which destination VoIP gateway to route the call to (i.e. multiple destination gateways may be supported). Considerations • Call transfer from a PBX extension to the other PBX may not be blocked by the PBX if the local PBX does not allow call transfers to Trunk Interfaces • Calls presented FXS to PBX can only provide ringing voltage to indicate call arrival.
9.h Mass analog connection – using a Vega 400 and a channel bank Where mass capacity of FXS and / or FXO interfaces are required it can be cheaper to use a Vega 400 together with a channel bank. Considerations • Ensure that the channel bank supports the required functionality, e.g. will it support hookflash, call cleardown detection. 9.i Analog long line extensions See “1 VoIP between sites” above. Version 2.1 Vega Gateway Scenarios. 16 March 2006 Page 28 of 33 ©2005-2006 VegaStream Ltd.
10. Appendix 1 – 3rd Party Products This list of 3rd party products is by no means a complete list of devices that Vega gateways have been tested with and interoperate with, but it provides an indication of the range of products available.
Genesys + ACD with integrated CRM solution GNU H.
Siemens’ OpenScape SIPExchange (PingTel) + SIP aware firewall SonicWall + SIP aware firewall + built in VPN tunnelling functionality (multiple tunnels) + can receive SIP INVITES and forward them to the appropriate internal VoIP devices + easy to configure SNOM 4S, proxy, media server, Nat traversal filter + Proxy, media server and NAT traversal available - needs to be run on a / some windows / linux PCs + Standalone version available Tangerine Inc SIP / H.
ITSPs and VoIP services Call UK Engin GossipTel Gradwell Hipcom Primus Pulver free world dial up Telic.net Version 2.1 Vega Gateway Scenarios. 16 March 2006 Page 32 of 33 ©2005-2006 VegaStream Ltd. Examples are given in best faith – ensure that you check the capabilities of systems before deploying them, especially the functionality of devices not designed and delivered by VegaStream. VoIPon Solutions www.voipon.co.uk sales@voipon.co.
11.
