T1 Bandwidth - Still a Useful Business Voice-data Platform?

With all the options available now ... e.g. ethernet, wireless, etc. ... is T1 bandwidth (and all it's flavors) even a viable choice as a network solution (or part of one) for today's businesses?

Though the T1 is a hold over from a technological universe from a galaxy far away. It is still widely used and ordered by customers big and small. There is an extremely large base of private IP networks that ride on T1 circuits. But if we want to be accurate, we should refer to it as DS-1 since what we are really talking about is the telephony network signaling format still of use and viable.

In my opinion, the telephony network is grossly under-estimated and understood by most network engineers. We do and will for a long time continue to build logical networks on the back of the physical telephony network. Large carriers have gradually built large packet data networks in parallel to the PSTN, but those networks still depend on the telephony network infrastructure for access.

The key issue is what other high speed services are available, and at what cost. Significantly higher speed services may actually cost less than a T-1. With the advent of Pseudowire technology, you can use a packet based service and still derive TDM interfaces such as T-1, T-3, etc., with all of the timing, functionality and QoS of traditional carrier services. The fact that many of these new services are packet based (IP, Ethernet, MPLS) means that you can keep your existing PBX or other equipment that needs a T-1 circuit, and transition to VoIP or other packet based applications later. Having done that, you still have significant bandwidth left over for internet access, video, VoIP, etc.

From the Network Service Provider (NSP) perspective, they would love to transport their TDM customer's traffic over their higher speed IP-MPLS backbone networks. Many of these NSPs continue to run the older TDM (ATM-SONET, Frame Relay, etc.) networks since their customers do not want to change. That said, they could provision the same services by using modern gateway products, and get the advantage of supporting the customers with a simpler Layer 2 network.

Remember that a T1/DS1 is just a pipe. If its configured for B8ZS it runs at 1.54 Mb before overhead, with AMI its 1.34 - you lose bandwidth due to framing and protocol overhead. Its 24 DS0's running at either 64 or 56 kb.

You can run any type of traffic over it, ATM. MPLS. HDLC. Frame Relay, Voice (you usually add echo can's to B8ZS with voice), VoIP ...

Whether its viable depends on what you need, what type of local loop or entrance facilities are available at the site you are supporting, how many ends you are buying, whether you use local or national providers, reliability, business applications (e.g. load from multi-media, conferencing, etc.), and a few other considerations ....

A T1 is still a viable option for the small business. The Telco can put a PRI in place and control/split the channels, leaving enough room for a meg of data and enough phone lines for the business to operate.

Most Telco providers will waive the install charge and give you a deal on any equipment they need to install in order to get your data working. At this point, the Small Business has to find a local tech to configure their firewall for access and they're up and running provided their phone system is in place.

In some "new construction" areas, no Fiber has been laid, the Telco isn't tariffed for splitting a T with a PRI, so you're stuck with DSL (unless you want to pay for multiple analog lines and a separate T1, running your bill over $1000/month). DSL is fine for bandwidth and offers many speeds, but a T1 is far more reliable than DSL in the vast majority of installs. The DSL will also require more effort to run an internal mail server by getting a static IP, DNS records, constant blacklisting of DSL users, ad nauseum.

A T-1 carries a significantly higher cost per megabit then other cheaper mediums. With the extra cost comes some specific benefits though. A T-1 carries an uptime guarantee. What this means is your circuit is monitored 24/7 for problems, and most carriers guarantee your internet or point to point will be up and functional %99.99 of the time. This is important if for example your company hosts it's own email server, and email delivery is mission critical.

In addition, a T-1 comes with "Quality of Service"(QOS). In a nutshell, QOS makes sure everything you send out gets processed in the same order it is sent out. This is attractive for companies who use Voice over Internet Protocol(VOIP) or companies who have a VOIP/PRI phone system. It makes sure your voice data comes across smooth and minimizes the delay between when you speak and when the other party hears you.

DSL is usually a cheaper solution, and usually provides higher bandwidth-per-circuit for smaller enterprises. However, beyond the lack of reliable SLAs, DSL circuits also lack the troubleshooting and more definitive fault identification systems that are integrated into T1 circuits and their associated hardware.

In short, for applications that require resiliency, T1s remain a safe bet on their own, or combined into multilink circuits.

If your company just needs access the internet, and none of the above scenarios apply to you, chances are business DSL is going to be a cheaper, faster option for your company.

ALWAYS keep this in mind too ..... your WAN or Internet connection should be determined by your needs, and not by an arbitrary opinion that T1 is old technology or a personal preference for an alternative. Until you or your company answers several questions about your intended usage, it doesn't make much sense to say what's viable among the various options available. Networking is not a "one size fits all" world.

All in all though, T1s are here to stay for awhile at least for small business use. T1 users aren't shrinking in numbers, but the T1s installed are simply capturing a smaller market percentage because of the number of businesses overall who need connectivity and the availability of Fiber/Cable/Whatnot.

The bottom line is that T1s are definitely a viable option for some. With the equipment already in place in most networks the deployment costs are pretty much non-existent. If the equipment is not in place it would probably be cost-effective to roll out newer technology such as Ethernet or FTTP (fibre to the premise).

Again, T1 bandwidth is definitely here to stay. Why? Because the T1 will always fit someone's business model.