hSo Guide To SIP Trunking
- 1. The hSo Guide to SIP Trunking The key facts you need to know about SIP hSo:you can do what you need to do
- 2. Copyright notice ©Copyright 2008 HighSpeed Office Limited, trading as hSo. No content from this guide, including trademarks, may be copied without approval. Neither this guide nor materials from it may be publicly displayed or distributed for any public or commercial purpose. Legal Disclaimer This free guide is provided with the understanding that HighSpeed Office Ltd (aka ‘hSo’) and its employees are not providing professional advice or services to you. This document is a guide to SIP Trunking. It is not a comprehensive guide to the subject. Before taking any action or making any business decisions on the basis of this document, you should take specialist professional advice from a competent professional. 2
- 3. Table of contents SIP Trunking for Beginners .....................................................................................................4 Is SIP Relevant To Your Business?.........................................................................................5 SIP Trunking Benefits..............................................................................................................6 The Risk-Free Hybrid Solution ................................................................................................8 SIP Trunk Reliability ................................................................................................................9 Things to Consider When Picking a SIP Trunk Provider ......................................................10 hSo SIP Trunking Solutions ..................................................................................................12 hSo Contact Details ..............................................................................................................12 3
- 4. SIP Trunking for Beginners When you make a phone call from your office, your phone talks to a mini telephone exchange called a PBX. Your PBX then talks to the public telephone network, connecting to it via a ‘trunk’. As the name suggests, trunks are far wider than normal phone lines. In fact they typically have 2 to 30 times the capacity of a standard phone line. Most trunks in the UK are ISDN circuits. But there’s a new kid on the block called SIP that’s gaining a lot of attention. SIP stands for Session Initiation Protocol. It is designed to set up connections between devices, such as computers, phones, PBXs, video conferencing units and servers. SIP can be used to support a wide range of services, including video broadcasts, instant messaging, multi-player gaming and telephone conferences. But the application we’re interested in is setting up virtual phone lines between your PBX and the public telephone network. This lets calls travel over your internet connection, and so reduces or eliminates the need for expensive ISDN circuits. Many recently manufactured PBXs support SIP. If your PBX doesn’t, don’t worry. You can still benefit from SIP, by adding a SIP-ISDN Gateway. This is a box that converts the ISDN signals from your PBX into SIP Trunk signals, and vice versa. 4
- 5. Is SIP Relevant To Your Business? SIP is relevant to you if: • You have ISDN30 or ISDN2 circuits • Your office gets its Internet Connectivity through a leased-line or a dedicated SDSL circuit SIP is not relevant if: • You don’t have any ISDN30 or ISDN2 circuits • Your office gets its Internet Connectivity through a contended ADSL service or through Wi-Fi 5
- 6. SIP Trunking Benefits SIP trunking offers a lot of benefits relative to ISDN: Only Only pay for capacity you need need Before we begin, let’s define a ‘channel’: a channel allows an outgoing call to be made, or an incoming call to be taken. ISDN2 forces you to buy two channels at a time. ISDN30 forces you to buy a minimum of 8, and a maximum of 30. If you have 30 and you want 31, you’ll have to pay for 38 channels (30 + 8). SIP can provide any number of channels, in increments of one. The only limit is your bandwidth. Cheaper connectivity Over the past few years, Internet connectivity prices have fallen through the floor. Over the same period, ISDN prices have stayed broadly unchanged. If you get your connectivity by renting ISDN lines, you’re probably paying more than you need to. SIP Trunking allows you to take advantage of falling Internet connectivity costs. costs No hardware costs With ISDN, if you need to add another ISDN circuit, you may need an additional ISDN line card for your PBX. The cost of these, including additional PBX licenses can set you back about £1500, plus installation charges. With SIP, adding new trunks to your PBX doesn’t require additional hardware. You would typically just pay a software license fee to your PBX manufacturer. ready Disaster Recovery ready SIP Trunking can increase your phone system’s resilience, by eliminating its dependency on individual circuits. Should a particular circuit go down, your calls can be routed over alternative paths. We’ll explain this in greater detail, later in this report. 6
- 7. Cheaper call rates rates A ‘hidden cost’ of ISDN is that ISDN calls are usually more expensive than SIP calls. Here’s why. When you make a call via ISDN, it is likely that your company uses something called Carrier Pre-Selection (CPS), to save money. This re-routes your calls, for the middle leg of their journey, so that they are carried by an alternative ‘carrier’ to BT. Typically these alternative carriers offer cheaper call rates, in order to entice phone companies to use them instead of BT. So CPS may save you some money, but not that much, as the ‘carrier’ has to pay to transport your calls from your local telephone exchange into its core network (before routing it to the person you are calling). SIP calls tend to be cheaper as they involve the carrier having to do a lot less work. Your SIP Trunk provider uses your Internet connection to transport your calls during the first part of their journey. The calls are handed over inside a data centre, going directly into the carrier’s core network. The carrier no longer has to worry about transporting your call from your local Telephone Exchange to their core network; because they have less work to do, they charge less, and this results in lower call rates. Typically, all outgoing calls made via a particular ISDN circuit are routed to a single carrier, even if that carrier has uncompetitive rates to some call destinations. SIP Trunking lets your phone company route your calls to a range of different carriers, allowing it to ‘cherry-pick’ the best call rates to a particular destination, and putting pressure on preferred carriers to lower particular rates. Some of the savings from this are passed on to you. Increased capacity Increased capacity by pooling Voice/Data connectivity connectivity When companies have 60 phones, they don’t rent 60 ISDN channels. Not everyone will be on the phone at the same time. For most of the time, they could probably get away with just 6 channels. But what if more than six people need to make or receive calls simultaneously? Then there’s a problem. Some people will find that they can’t dial out, because all the channels are in use. To avoid these problems, most companies pay for more ISDN channels than they need. In the above example, they might rent 10 channels, rather than 6. They base their decision on the maximum number of simultaneous phone calls expected at peak times, rather than the number typically in use. For most of the day, a vast portion of their expensive ISDN channels go unused. The same goes for corporate Internet connections. Most of the time, far less than 100% of the connection is being used, but there will be sporadic bursts to 100% utilisation. By pooling the phone connectivity and the Internet connectivity, and prioritising the phone calls over the data transfers, most companies could increase the simultaneous number of phone calls that could be made at peak times, while letting the Internet connection use any spare capacity left by the typical usage of their phones. 7
- 8. Risk- The Risk-Free Hybrid Solution If you’re convinced that SIP offers benefits, but would prefer to ‘dip a toe in the water’ before getting rid of your ISDN lines, there’s a hybrid solution that will appeal to you. Here’s how it works. Your SIP Trunk provider would put a box between your PBX and your ISDN lines. All incoming calls to your office would go over ISDN, just as they do now. All outgoing calls would be re-routed by the box, to go over your Internet connection, using SIP trunks. In the event that your Internet connection were to go down, the calls would go out over your ISDN lines, just as they do now. The result is you get cheaper call rates (because the calls you make go out via SIP rather than ISDN). You can reduce the number of ISDN channels you pay for, if you wish, but still have some left, just in case they’re needed. And you also get improved resilience: Traditional ISDN Solution Outbound SIP Solution, with ISDN Backup Fault Inbound Calls Outbound Calls Inbound Calls Outbound Calls OK ISDN Connection Down LOST LOST LOST (Unaffected) OK OK OK OK Primary Internet (Unaffected) (Unaffected) (Unaffected) (Switches to using Connection Down ISDN or backup Internet connection) 8
- 9. SIP Trunk Reliability SIP has many benefits over ISDN, but ISDN is proven, whereas SIP is relatively new. Is SIP trunking as reliable as ISDN trunking? With the right set-up, the answer is YES. In fact, with the right set-up, you’ll get improved reliability. Traditional ISDN Solution SIP Only Solution SIP With Backup Solution (Your current solution) (Without backup path) (With ISDN or Internet backup) Inbound Outbound Inbound Outbound Inbound Outbound Fault Calls Calls Calls Calls Calls Calls ISDN OK OK OK OK Connection LOST LOST Down (Unaffected) (Unaffected) (Unaffected) (Unaffected) OK OK LOST LOST OK OK Primary (Unaffected) (Unaffected) (Switches to (Switches to Internet using ISDN using ISDN Connection or backup or backup Down Internet Internet connection) connection) The right set-up to ensure reliability involves: • VOICE PRIORITISATION – the SIP trunks should take priority over the rest of the traffic, as phone calls aren’t delay-tolerant or loss-tolerant. • AUTOMATIC ‘FAIL-OVER’ TO BACKUP CONNECTION – there must be at least one backup-up connection. This can be a backup internet circuit, set to automatically take over if the main link goes down. Or it can be a left-over ISDN circuit (with fewer channels than before). • DIRECT CONNECTIVITY TO YOUR SIP TRUNK PROVIDER – your SIP trunks and Internet connection should be from the same company, to ensure your phone call quality is good. Although we talk of your ‘Internet connection’, in reality you only want your calls to travel over the dedicated, uncongested bit of the Internet that you control, so that traffic congestion doesn’t ruin your call-quality. 9
- 10. Things to Consider When Picking a SIP Trunk Provider provider Direct connectivity to your SIP trunk provider Voice over IP (VoIP) phone calls are sensitive to packet loss, latency (delay) and jitter (variations in delay). If you’ve ever had a mobile phone conversation with someone whose signal is poor, you’ll know the effect these things can have on call quality. To avoid such problems, it’s important to have a low packet-loss, low latency, low jitter connection to your SIP trunk provider. And the easiest way to get that is to get a direct connection to their network. That way, you avoid call-quality issues. A direct connection also improves security, as your phone call traffic is only visible to your SIP trunk provider, and not to a separate ISP and its IP transit providers. services Additional services If you are going to have a direct connection to your SIP trunk provider, you might as well benefit from economies of scale and use that link for other services, besides phone calls, such as Internet Access, connectivity to other offices and connectivity to staff working from home. If your SIP trunk provider doesn’t provide these services, you can’t aggregate your connectivity bandwidth to take advantage of economies of scale. Experience The adoption of SIP is typically quite smooth, but there can sometimes be minor glitches. So choose a provider that has experience at implementing SIP and helping customers implement it. Avoid ones that just hand out SIP trunk logon details and leave you to configure it on your own, with only an FAQ for help. power Buying power The more phone calls your provider buys from its suppliers each month, the cheaper rates it gets, and the cheaper rates it can pass on to you. Look for a provider that buys millions of minutes of talk time from its suppliers each month. That way, you’ll get better value. 10
- 11. independence Carrier independence Ensure your SIP trunk provider uses multiple carriers. This ensures that if there’s a problem with a particular carrier, calls can be routed to an alternative one. Using multiple carriers enables your SIP trunk provider to put greater pressure on their carriers to reduce pricing. They can play the different carriers off against each other, and route the phone calls to Tier-1 carriers offering the best value. Longevity The Telecoms industry is brutal. Every year, many telecoms companies come and go, leaving customers in the lurch. Ensure you pick a SIP trunk provider that has been around for years, is profitable, and will be around for many years to come. infrastructure Resilient infrastructure Some SIP trunk providers operate out of a single data centre. If anything were to go wrong in that location, for example a power cut, a fire, or flooding, their service would be taken down. It’s essential that your provider has carrier connectivity and soft- switches in multiple geographically dispersed data centres, to ensure you’ll get a reliable service, whatever happens. 11
- 12. hSo SIP Trunking Solutions Our SIP Trunking solutions provide: • Carrier-independence • Resilient services, thanks to our operation out of multiple data centres • Attractive call rates, thanks to our leverage with carriers We’ve been providing a full range of telecoms services for over 8 years, including SIP Trunks for 5 years. We provide a full range of telecoms solutions including: • SIP Trunks • Standard phone lines • ISDN circuits • IP-PBXs and • Complete phone systems We can help you get the most out of your connectivity by enabling you to combine SIP-Trunking with site-to-site connectivity, internet access and VPNs. To find out more, call us today on 08700 638 739 hSo Contact Details hSo, Epworth House, 25 City Road, London, EC1Y 1AA 08700 638 739 http://www.hso.uk.com 12