Do we have an onsite PBX or IP PBX?
A PBX (private branch exchange) is a piece of hardware located in your office that handles all of the features of your calling system. This is what we call “the brains” of your phone system; handling extension dialing, ring groups, voicemail, etc. An IP PBX is the same thing but transmits voice using IP (Internet Protocol). An IP PBX, or an older PBX with an IP Adapter, is required for SIP Trunking.
How many simultaneous calls do we need to make?
The number of simultaneous calls does not always equal the number of employees you have in your business. If your company has 10 employees, you may only have, on average, 3 people using the telephone at any one given time. Adding some “wiggle room” your answer may be “5 simultaneous phone calls”. In which case you would need to purchase 5 SIP Trunks. This is one of SIP Trunking’s greatest advantages, especially if you’re coming from a PRI solution. In a PRI solution, you are provided with 23 trunks, even if you only ever make 5 calls at once. If you’re interested in the major differences between PRI vs SIP Trunking please check out our article.
How much bandwidth do we currently have?
Perhaps the easiest question to answer, requires you to check your internet provider’s invoice, which will usually list the bandwidth that you are paying for. Once you know this number and using your answer from the question before, you can then figure out how much bandwidth you need. Since you will be transmitting phone calls over your existing data connection, you will need to have enough room for all of your SIP Trunks plus your existing data usage. In some cases, this may require an upgrade to your data connection bandwidth. Different providers may use different compression methods, this table can help you determine how much bandwidth you need for the two most commonly used compression codecs.
|Compression Codec||Recommended Bandwidth per trunk||x Number of seats (example)||= Total required bandwidth for SIP Trunking|
|G.711||83 Kbps||5||415 Kbps|
|G.729A||27 Kbps||5||135 Kbps|
You will need to check with your SIP Trunking provider as to what Compression Codec they use so that you can calculate your bandwidth requirements. Less compression typically means better quality, so you are looking at about .5Mbps for every 5 SIP Trunks you purchase. In addition, you will need to ensure what codecs your PBX can support.
Does our company require a backup solution?
Some businesses lose money every minute that their phone systems are down, other businesses have more flexibility. Since your Internet and Voice communication services are sharing a single line, and depending on how vital that phone service is, you may want to consider a backup solution to your SIP Trunking services. Whether this is a couple of additional POTS lines coming in or your SIP Trunking provider forwarding calls to cell phones in the event that your PBX can not be reached.
Do we really need SIP Trunking?
“If it ain’t broke, don’t fix it” – If your company doesn’t have an onsite PBX (which can be a costly investment) then that investment in SIP Trunking may not be the right solution. First and foremost, it’s important to write down and establish exactly what your business goals are when seeking out any sort of Voice or Data provider. There is no “one size fits all” when it comes to the Telecom industry – and don’t let anyone tell you otherwise! By giving a potential service provider your business goals, they should be able to evaluate what technological needs will help you reach those goals. Maybe PRI lines make more sense for your business, or maybe a hosted VoIP Solution is the right answer. By understanding exactly what your business goals are, you can avoid making a purchase that answers questions you aren’t asking. When we do our side by side comparisons for prospective clients, we see long laundry lists of services that businesses are paying for that they never need or never use; many times they don’t even realize they’re paying for these services. You should only be paying for what you’re using.