Analog POTS Transitioning to Cellular Wireless


The goal of this document is to graphically represent the financial benefit of migrating from 1MB business (Analog POTS) to cellular wireless circuits. For purposes of the Use Case, we will be discussing business applications, and use for Serial Console access, aka Out of Band Management.

There are numerous reasons why a business may elect to migrate from analog Out of Band Management to cellular wireless. Cell Wireless can provide improved performance, faster installations, and more network status visibility. For the purposes of this document we will be focusing on financial impact of making the transformation.

Analog phone lines have been in use for business applications for over a century. The service, consisting of a twisted pair of copper wireless from a telco central office, was a mainstay of consumer and business users for generations, as POTS provides a high continuity and service, even in local power outages. The
offering has been severely curtailed, and in many cases sunset by the local telecommunications providers. Some reasons for shift in technology by service providers include: expensive provisioning and maintenance of the network resource, as well as an abundance of suitable alternatives such as Cellular Wireless, Fiber, and VoIP, with improved Quality of Service (QoS).

Because of the maintenance and labor costs inherent in maintaining analog networks, the costs in many cases have eclipsed any profits. Many of the largest global telecommunication’s providers have pledged to sunset POTS services altogether. In many global markets outside of North America, businesses are unable to purchase an analog phone circuit.

Historically Out of Band Management relied heavily on analog phone lines. The circuits were inexpensive, self-powered, and nearly ubiquitous for decades. Because of the “always on” status of an analog circuit, businesses have generally relied on the service. Today many businesses are transitioning to 3G/LTE/5G cellular wireless service for Out of Band Management. Cellular wireless is a ubiquitous, inexpensive, and operates at greater speeds than comparative analog products. The major limitation to cellular service for Out of Band Management is signal strength in rural locations and signal issues at datacenter locations.

The telecommunications industry has been investing heavily in cellular wireless service for the past several decades. In the United States the number of cell sites has increased four-fold, from 100,000 locations in 2000, to nearly 400,000 in 2019*. The proliferation of cellular wireless has transformed the way people do business, as evidenced by the decrease in the numbers of traditional phone lines, and abundance of new and competing technologies. The large quantity of, and continuing improvement of cellular technology, will continue to be adopted by businesses and corporations globally, providing tremendous network speed gains at reduced costs.

As previously stated, Cellular wireless has several key advantages over analog circuits, and in some cases is the only alternative, as dictated by the availability of Service Provider’s offerings. Not to be discounted, the administrative costs of operating an analog OOB ‘network’ with multiple carriers can be an administrative challenge.

Analog telco lines are priced by service provider, based on rates set at the state level and dictated by law. Prices for analog circuits vary, depend on site location. Because of local pricing and regulation, analog (POTS) circuits have dramatically different price points, typically between $25 – $150/month per circuit. In CDI’s customer work over the past several years, we have used $50/month as a reliable cost for purposes of demonstration (although prices are often higher).

Cellular wireless conversely prices out in the $9-$15 range for a circuit suitable to offering Out of Band Management. As indicated above, we will use $12/month for the average (5MB) circuit price. This price is fixed for global applications and assumes a, “pooled” data arrangement which prevents cost overrides.

Number of POTS Circuits (P)                      Monthly Cost UDS (C)                     Annual Cost USD (PxCx12)
500                                                                            $50                                                              $300,000

Now with Cellular Wireless replacing Analog POTS

Number or LTE Circuits (L)                        Monthly Cost UDS (C)                      Annual Cost USD (LxCx12)
500                                                                            $12                                                              $72,000


Cellular wireless circuits may have potential coverage issues based on location and environmental factors, but clearly, are a more cost-effective solution for Out of Band Management. Some suggestions to working with your Out of Band Management CPE manufacturer or provider:

Ensure you are using Private / Static IP addresses for cell wireless Out of Band Managementavoid the public internet and the associated issues (DoS attacks and security issues).

Have a plan to test your site locations for cellular efficacy. A general rule of thumb is if you can browse a webpage from the physical location where the CPE is being installed, Out of Band Management will work well. An on-premises representative can also use their cellular wireless phone to, “field test” signal strength and determine how a location would accept the move from analog to cell wireless. Signal Strength can run from -51dBm to -113dBm. Values closer to – 51dBm are stronger. A signal beyond -98dBm is not considered strong enough to work properly.

Strongly consider using a Private APN for your cellular wireless SIMs. A private APN can be provided by your service provider or CPE manufacturer; akin to a private VPN, this arrangement isolates your SIM cards from other network operators.

Consider the ROI for a physical CPE upgrade. How much can you save in network costs? How many months will it take you to recoup your CAPEX in equipment? Generally speaking, Out of Band Management equipment upgrades will pay for itself in 12-18 months (based on replacement cost/new purchase). With an effective lifespan of 10+ years, transitioning from analog POTS to cellular wireless, can provide significant overall savings to your Enterprise