TDM stands for Time Division Multiplexing. It’s the technology behind traditional phone service. VoIP stands for Voice over IP and is the transmission of voice communication over the internet.
The following are how particular TDM services compare to their VoIP counterparts:
PRI vs. SIP – The strengths of PRI are uptime and call quality. Nothing provides better call quality than analog phone service. PRIs provide an uptime of 99.999%, which equates to 5 minutes of downtime per year. The restrictions of PRI are that it is a static service, providing 23 channels for voice communication. What if a business only needs 18 lines? Even more challenging is if a business needs 25 lines. If they are utilizing PRI, they must either make do with 2 fewer lines or deploy an extra PRI and have 21 superfluous lines. Because PRI is static, if any of its channels are not in use, they can’t be used in a different capacity, they just sit dormant.
SIP trunks aren’t as stable as PRI and call quality, even with Quality of Service, is slightly less than analog call quality. The big advantage SIP has over PRI is its flexibility and that it’s a dynamic service. SIP trunks can be purchased in any increment. If a business needs 25, they can order 25. When SIP trunks aren’t in use, the bandwidth they utilize is freed up for other uses, such as data transmission.
POTS vs. SIP – Like PRI, POTS advantages are uptime and call quality. POTS lines are even more stable than PRI because they have their own power supply. But POTS lines are laced with taxes and surcharges. The taxes and surcharges included on one POTS line approach the monthly cost of a single SIP trunk.
SIP trunks provide much greater phone number flexibility. A SIP trunk can utilize a phone number from anywhere in the country. SIP delivers more information and functionality because it rides over the internet. The only information that can be delivered using POTS is Caller ID. For instance, SIP can deliver screen pops, including customer account information, onto an employee’s computer screen when a customer call arrives.
Long Distance – Almost all long distance today rides over the internet. It’s much more economical to transmit long distance across a data network, because fixed call channels aren’t required. With TDM, each call requires a separate channel. If carrier wanted the ability to transmit one million long distance calls per month in a TDM environment, they would require close to a million fixed channels. With VoIP, bandwidth is all that is required.
Integrated T1 – Analog integrated T1s offered a fixed number of phone lines and whatever bandwidth was left over, could be used for data transmission. If a business needed 12 phone lines, for example, since a T1 provides 24 channels, half the channels would be needed for voice and the other half would be left for data transmission. In this example, half a T1 would provide 768k of bandwidth for internet access or other data transmission.
Integrated T1s utilizing VoIP technology offer dynamic bandwidth. Each call requires roughly 64k of bandwidth. Instead of dividing the T1 in two and using one half for voice and the other for data, dynamic T1s allow the bandwidth required for a phone call to be freed up for other uses when the call is completed. If no one is on the phone all the bandwidth is available for other uses. Instead of limiting itself to 768k of bandwidth, a business would have twice that amount available if none of its employees were on the phone.
Phone Systems – Today, phone end sets are mini computers. Incoming calls can be managed in a number of different ways with prompts that appear on a phone’s display. Voicemails can be delivered to a recipient’s email inbox. Calls can be recorded and stored as WAV files. When voice communication is transmitted over data circuits, so much more is possible.
If you’re company is considering implementing VoIP, contact CarrierBid telecom consulting today.