Frequently Asked Questions

An IP•Tube T1/E1 unit transparently carries the proprietary signaling that T1 and E1 circuits rely on, so voice and data traffic keeps flowing correctly once it's moved onto an IP or Ethernet network. Your existing PBXs, switches and TDM equipment keep working exactly as they did over a leased line — they just don't know the underlying transport has changed.

IP•Tube T1/E1 units are available with one to four T1/E1 interfaces and one or two 10/100 BaseT Ethernet ports. Each T1/E1 interface can be independently configured for protocol, compression, packet size, buffering, clocking, framing, coding and channel (DS0) assignment — so a single chassis can be tailored to a wide range of circuit requirements.

IP•Tube T1/E1 models wrap full or fractional T1/E1 TDM circuits — including their framing and signaling bits — inside standard IP packets. The QT1 models do the same for up to four circuits simultaneously. The result is a transparent TDM-over-IP connection that interconnects PBXs, telecom switches and other T1/E1-based systems across LANs, WANs, MANs and wireless Ethernet links.

The IP•Tube T1/E1•C adds optional lossless data compression, which is especially useful where bandwidth is limited — point-to-point or point-to-multipoint wireless, HFC cable modems, xDSL, power-line Ethernet, or the public Internet.

The compression engine continuously watches each DS0 for idle or repeating data, so bandwidth isn't wasted carrying silence or redundant patterns — in the best case delivering up to a 56:1 bandwidth savings. The achievable ratio depends on the Frames-Per-Packet (FPP) setting: the IP•Tube can encapsulate anywhere from 8 to 40 T1/E1 frames per IP packet. If every byte in a DS0 channel is identical across all frames in a packet, only one byte is sent instead of all of them. Taken to the extreme, a fully idle or fully redundant T1 circuit ends up needing only the equivalent of a single frame's worth of data per packet, rather than 8–40 frames.

Yes. IP•Tube T1/E1 sets the Type of Service (TOS) byte on its IP packets, which lets intermediate routers and switches recognize and prioritize the real-time TDM traffic as it crosses the network. QoS has to be enabled on every router or switch in the path between IP•Tubes to be effective.

The simplest way to configure this is by UDP port rather than IP address: Engage has registered UDP port 3175 with IANA specifically for this traffic, and that's also the IP•Tube's default communication port (it's configurable if you need something else).

Encapsulating T1/E1 data into IP/UDP packets for transport over Ethernet adds a fixed 44 bytes of overhead per packet, made up of the Ethernet, IP and UDP headers. Worth factoring in when calculating Ethernet bandwidth requirements — increasing the Frames-Per-Packet (FPP) setting spreads that fixed overhead across more data, reducing its relative impact.

IP•Tube works over any IP/Ethernet path — a private WAN, MPLS, microwave or wireless link, or the public Internet. A private or QoS-managed network is recommended for latency-sensitive or high-utilization TDM traffic, but it isn't a hard requirement.

No special hardware is required — IP•Tube connects to any standard 10/100 BaseT Ethernet port. Existing routers and switches only need to support basic QoS/TOS-based prioritization if you want to guarantee priority for the TDM traffic on a congested network.

IP•Tube is Engage's core TDM/serial-over-IP circuit emulation product line. BlackTube is the encrypted counterpart — it performs the same circuit emulation but adds hardware encryption to protect the circuit's data in transit, which matters for utilities, defense, and other security-conscious deployments.

Yes. Engage's SynAPS Automatic Protection Switching products pair with IP•Tube deployments to detect a circuit or path failure and automatically switch to a backup path, minimizing downtime for critical circuits.

Yes. Because every IP•Tube/BlackTube model just encapsulates its circuit type into standard IP/UDP packets, different circuit types (T1, E1, RS232, RS530, 4-wire analog, etc.) can share the same Ethernet or IP network simultaneously without interfering with one another.

Reach the Engage support team directly at 1-831-688-1021 or toll-free at 1-877-ENGAGE4, or visit the Technical Support page for documentation, MIBs, and product resources.

• A DS0 is a 64 Kbps voice/data channel — the basic building block of a T1 or E1 circuit.
• A full T1 circuit carries 24 DS0 channels. Each frame allocates one byte (8 bits) per DS0 plus 1 framing bit, for 193 bits per frame: (24 × 8) + 1.
• A full E1 circuit carries 31 DS0 channels. Each frame allocates one byte per DS0 plus a framing/signaling byte, for 32 bytes (256 bits) per frame.
• The Frames-Per-Packet (FPP) setting controls how many T1/E1 frames get encapsulated into a single IP/UDP packet. Raising FPP reduces the relative effect of the 44-byte encapsulation overhead.