Most businesses will find SIP Trunks to be more affordable than copper lines or a PRI. While cost is not the only factor to consider when selecting a communications platform, it is usually one of the first topics of discussion. Some small brick-and-mortar businesses that require no VoIP features and already have copper lines in their building will find that copper lines are more cost-effective in the short-term.
Copper lines and SIP Trunks can both have the same level of security; however, SIP Trunks require that your IT infrastructure be intentionally designed to protect voice traffic. For this reason, PRIs and copper lines are considered to be more secure. This is not necessarily true, since copper lines can be vulnerable to interference and interception. Ultimately, SIP Trunks, with adequate IT security support, are more secure than traditional copper lines.
If your business regularly grows and shrinks, typically seasonal business or start-ups, then SIP Trunks are the best choice. They can be scaled up or down in minutes and you only pay for what you needs. Copper lines and PRIs require physical infrastructure to function and you rely on the carrier to make changes. Because the carriers of copper lines are large companies, such as AT&T, these changes can take weeks to apply.
Copper lines have a reputation for reliability since they don't rely on the internet. However, PRIs can be damaged by storms, vandalism, or degradation over time so their reliability is not as absolute as once thought. SIP Trunks rely on internet bandwidth to carry voice so, in the past, when the internet went out so did communications. Additionally, 50Mbsp was a huge amount of bandwidth that most businesses did not have access to or the budget for the bandwidth needed to support SIP Trunks. That has changed in recent years as gigabyte speeds become more available and affordable. Cellular failover options can keep voice traffic up and running even when the internet goes down.
No one selling copper lines wants to acknowledge the hard truth that copper lines have an expiration date. Verizon announced it would pull its copper wire service in 2018. AT&T has been pushing legislation that allows them to disconnect copper lines in the near future. The trends are pretty clear that copper has fallen out of favor with telecom giants. If you plan to be in business for longer than 5 years, then your wisest decision would be to plan for the future and implement SIP Trunks. The internet isn't going anywhere but copper lines are certainly on their way out.
While we strongly recommend SIP Trunks for all of our businesses there is a case to be made for copper lines and PRIs. If you run a large business with more than 40 employees and experience high call volumes consistently, then you will find a cost-savings in PRIs. This savings is because SIP Trunks have to be purchased in channels, so 23 channels are more expensive than a PRI with 23 lines. This may not be the case as for very long, as SIP Trunks become more affordable as services scale.