Keymile UMUX – Multiservice access solutions

Comprehensive Functionality

The UMUX platform provides carrier-grade reliable multi-service multiplexing and aggregation functions over copper and fibre networks. A variety of voice (POTS, FSX, FSO, ISDN) and data (e.g. G.703, V.11, V,24, V,35) interfaces, SHDSL and Ethernet (including PoE+ and EoS) services are available. 

The modular and flexible housing provided by the UMUX 1500 (8U, 21-slot) and UMUX 1200 (4U, 8-slot) 19” subracks provide the perfect solution for all applications and locations, offering redundant controller and power supplies.

‘Legacy’ telecoms history

The UMUX SDH product portfolio was originally launched 1991 by Ascom, which subsequently became Keymile.

In 2003, by when 70,000 units had been deployed worldwide, the ‘enhanced’ UMUX multiservice access platform was introduced, offering the delivery of ATM, TDM and IP based services from the same platform, with support for IP/Ethernet, ADSL, VoDSL and G.SHDL.

Keymile was sold to ABB in 2017 when the UMUX range was discontinued, and then was acquired in 2019 by DZS. 

Continuing to provide operational service

The UMUX, together with the UNEM network management system and ‘sister’ LINERUNNER and MILEGATE products, continues to provide operational service with various global Operator, Utilities and Transport companies. 

@YellowsBestLtd supports requirements to maintain these networks by supplying various spare part items from refurbished and surplus stocks in perfect working order.  

There follows a list of the main elements that are typically provided, though other items can be provided. Please let us know of any specific requirements you may have. We look forward to being of assistance.

Part CodeUnit typeDescription
A31A1679U1500-CSU1500 Core R2 (DC) for 19″ mounting (incl. Subrack, POSUM, COBUX 128x2Mb/s XC)
A30A0205DATAS-FUData Interface unit.  Multi-Interface V.35, V.24/V.28, X.24/V.11, RS485, Ethernet, 4 ports, all options
A24A3323LOMIF-FU2 Mb/s IF (E1), 8 x G.703 Interfaces
A24A3651COBUX-FUControl Unit Standard,128x2Mb/s XC
A21A2865EXLAN342POTS FxO Interface Unit, 12 ports, complex impedance
A31A7871GECOD371Data IF 64kb/s G.703 codir., 8 interfaces
A24A3338LOMI4-FU2 Mb/s IF (E1), 4 x G.703 Interfaces
A24A7979POSUM306Power supply unit -48VDC 85W
A30A1442SUBH3-FUPOTS FxS  Interface Unit, 30 ports
A31A7873SULIS393ISDN Interface Unit Subscriber side, ISDN BA 2B1Q, 8 interfaces
A23A9927SYNAC-FUSDH Access bridging unit SBUS-PBUS, 8xVC-12; no external IF
A24A1989TUPON-FUOptical Trunk Interface 8Mbit/s 1xopt.(o), 4xel.(e), 1550nm, PBUS access

Nokia ‘Dynanet’ Telecoms – Stock disposal

‘Last chance’ for spares!

The Nokia ‘Dynanet’ family of PDH Transmission telecoms products has served customers well for the last 20+ years, and indeed some networks continue providing good operational service. 

Dynanet Subtrack

@YellowsBestLtd has supported requirements to maintain these networks by supplying various spare part items from refurbished and surplus stocks in perfectly working order.

However, demand has recently reduced and warehouse space is needed, so now the time has come to recycle / dispose of a large proportion of the remaining equipment. Consequently, there remains a short-term opportunity to obtain any items still required to maintain existing deployed infrastructure, before the products are gone.

Here is a stock list of the main items currently available, though there may be a few additional parts that can be supplied. Hence, please check and if you do have any requirements, please let us know – before it’s too late! We look forward to hearing from you.

Part  NumberDescription
24204TPSO H/W Module
CC 24002DB2 Branching Unit, B2 2×2 Mb/s 75 ohm
CC 24011DB2 2 Mb/s Switching Unit, X2 75 ohm
CC 24101DN2 Interface Unit (IU2) 2×2 Mb/s 75 ohm
CC 24111DN2 Control Unit (CU) 75 ohm
CF 24186DN2 19″ Subrack
CF 24186.09DN2 Subrack 19″, grey-L91 EMC
CG 24170DN2 Bus Power Unit (BPU)
CG 24171Extended DN2 Bus Power Unit (EBPU)
CU 24013Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75 ohm
T30506.0917-slot DYNANET Subrack
T30851.02Subrack Power Adapter (SPA)
T37870.01NDM ACM2 19in 17-slot subrack
T37871.01NDM DN2 19″ 17-Slot Subrack
T37882.01NDM DC Unit (NDUe)
T37882.02NDM DC Unit (NDUe)
T37885.01NDM Ring Generator
T37889.01NDM Backup Unit (NBU)
T65520.01ACL2 RM DC Power Gen
T65580.01ACL2i PF GEN Line Terminal Card
TA 21513Optical Line Terminal Repeater 2-8 M, 1300 nm LED MM/SM
TA 21516Optical Line Terminal Repeater 2-8 M, 1300 nm LASER SM
TC 21101DM34 Mux Card
TC 21301DM8 Multiplex Equipment, 75 ohm
TC 21705Supervisory Substation
TC 21710.01TMS Adapter
TG 21261Ring Generator 25HZ 15W
TU 21122.5Data Interface Unit (DIU) 48..64k V.11 10ch
TU 21124Data Interface Unit (DIU) NX64k V.11/V.35/X.21 2CH
TU 21124.05Data Interface Unit (DIU)
TU 21125Data Interface Unit (DIU) 48..64k with sync, X.21
TU 21205Channel Unit SUB/SUB
TU 21206Channel Unit SUB/SUB
TU 21215Channel Unit SUB/EXCH
TU 21216Channel Unit SUB/EXCH
TU 21234.20Channel Unit E&M/VF-P, 10 CH, 20 E&M CH
TU 21236.10Channel Unit (CU) 8ch E&M/uP: 2xe&m/vf
TU 21255.01Channel Switch, 4 PORT
TV 21640.08Power Interface Adapter DC

Legacy and New Infrastructure Spares

Most Customers’ infrastructure systems now consist of a wide range of technologies from the very old to relatively recent, having been built to serve operational requirements for a number of years. In many cases, these requirements don’t significantly change, and it therefore makes sense to keep these systems in place to maximise the use of the investment and avoid whole-scale change-outs that would be costly, disruptive and unnecessary.

@YellowsBestLtd locates hard-to-find replacement spare parts to keep legacy infrastructure in operational service that has been deemed ‘obsolete’ by the manufacturers, as well as supplying additional spares for newer systems that can be used to increase capacity or provide alternative interfaces.

Typically we provide refurbished spares, tested and working, but often it is the case that unused products from surplus stocks can be supplied. Hence for both old and new systems, we are usually able to source parts at very commercially competitive rates and with short lead-times.

Here is a selection of items that we’ve recently been helping customers procure or obtain parts for. Keen to hear what requirements you may have, so please get in touch.

Alcatel AnyMedia Access System
Bosch MIC-400, -550 and -7130 Cameras
Dialogic I-Gate 4000 System
Huawei UMG8900 Node
Marconi ST68NB Matrix and 1HAT60558ADV
Meraki MS250 switch and MR52 access point
Motorola Terayon DM6400 Network CherryPicker
Nokia Dynanet PDH Subrack and 9500 MPR ODU
Pelco S5220 Spectra CCTV Camera
Siemens SRT1 C Base Band Unit

Reduce Reuse Recycle

@YellowsBestLtd helps Customers with their operational needs, and one aspect is to #Reduce the demand for avoidable whole-scale replacements through a combination of supply for #Reuse of refurbished spares and repair of system elements. When removal and disposal of no-longer serviceable infrastructure parts is necessary, we can also assist with the resale and #Recycle for ‘value recovery’ of valuable materials.

Most customers have implemented their private network infrastructure systems over a number of years, and for many their operational requirements have not changed. Consequently, it makes more sense both financially and environmentally to maintain these systems rather than embark on complete change-outs. We can assist by supplying critical and hard-to-find spare parts and hardware repair services, even when the systems have been declared ‘obsolete’ (i.e. no longer in production) by the O.E.M.

Eventually there does come a time when it proves necessary to remove and replace network infrastructure. Rather that simply discarding the old system elements, we can provide ‘value recovery’ to the Customer by means of resale of working parts and recycling of components, extracting useful materials. This often proves financially beneficial, generating a source of funds which helps to pay for the replacement systems, as well as providing an ethical means of disposing of unwanted parts with the least environmental impact.

Please get in touch should you wish to discuss your operational requirements and see how @YellowsBestLtd can be of assistance.


Recommended reading on the wider aspects of ‘The Future of Waste’ can be found in:

@TheIET @EandTmagazine Volume-12_Issue-11

Nokia ‘Dynanet’ – Still Operating, Still in Demand!

Nokia ‘Dynanet’ PDH Telecommunications Product Portfolio

Still Operating, and Still in Demand!

We’re pleased to have recently helped Customers locate additional spares of this incredibly reliable and therefore popular telecommunications infrastructure equipment.

The range was originally produced by Nokia, and has been extensively deployed and in operational service around the world for over 20 years. It has formed the backbone of PDH and Access networks for many Customers across the Telecom Operator, Utilities and Transportation market sectors.

Recent Requirements

We’ve recently supplied Customers with these spare parts:

  • Smart Branching Unit (TU 21743)
  • DC/DC converter -24..-48V / -48V,-60V (21263)

These represent popular choices, but see below for an extended list of other immediately available items.

Future Dependability

It makes sense for Customers to use these spares as replacements as well as to add additional capacity to their existing networks, given the faultless performance of the products, rather than undertake costly and time-consuming wholesale replacements, given that in many case their basic telecommunications  requirements have not  changed.

Plus the ‘Dynanet’ product range has proven itself to be dependable over an extended period. How many of the latest products will be available in 5 or 10 years’ time, let alone in over 20 years?

Dynanet – an overview

 Nokia DYNANET is a family of multiplex, branching, cross-connect and line equipment.

The DM2 equipment has been designed for multiplexing analogue speech and signalling as well as data channels of different bit rates into a common 2 Mbit/s frame. The dynamic branching equipment DB2 and the cross-connect equipment DN2 increase the flexibility and application range in the DYNANET family.

The DYNACARD data channel unit selection covers the bit rates from 0.3 kbit/s up to 1984 kbit/s compliant with the V- or X-series of the ITU-T Recommendations. Other DYNACARD channel units provide specialised interfacing functions for Voice and Data applications.

The heart of the equipment is a MUX unit which is common to all channel and special units of the DM2 system. The MUX unit communicates through a 2 Mbit/s internal bus with the tributary units and carries out the 2048 kbit/s framing according to ITU-T G.732 standard.

The common MUX unit also inserts the signalling information into time slot 16 or provides the time slot 16 as a 64 kbit/s data interface, e.g., for use with a separate signalling equipment.

Analogue and digital services are realised with interface-specific channel units that connect to the DYNACARD bus. The channel units contain from one to ten voice channels, depending on the complexity of the interface.

Each individual voice or data channel can use any 64 kbit/s time slot, several time slots or only part of the capacity of one time slot. The allocation of time slots to different voice/data channels is independent of physical unit placement.

The DYNACARD VF channel unit selection provides analogue interface with signalling adaptation ranging from subscriber signalling to various types of junction line signalling. The signalling can be either channel associated or common channel signalling. In subscriber applications subscriber line testing is also available.

Immediately available from Refurbished Stock

Here is a list of items currently available from refurbished stock. All in excellent working condition, and can be delivered in a matter of days. No long lead time! But do remember that many items may be in short supply, so worth acting now and purchasing any spares you might need to avoid future disappointment!

Part Number Description
24204 TPSO H/W Module
CC 24002 DB2 Branching Unit, B2 2×2 Mb/s 75 ohm
CC 24011 DB2 2 Mb/s Switching Unit, X2 75 ohm
CC 24111 DN2 Control Unit (CU) 75 ohm
CF 24186.09 DN2 Subrack 19″, grey-L91 EMC
CG 24170 DN2 Bus Power Unit (BPU)
CU 24013 Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75 ohm
CU 24101 DN2 Interface Unit (IU2) 2×2 Mb/s 75 ohm
T30506.09 17-slot DYNANET Subrack
T30851.02 Subrack Power Adapter (SPA)
T37870.01 NDM 19in 17-slot subrack
T37882.01 NDM DC Unit (NDUe)
T37889.01 NDM Backup Unit (NBU)
T65580.01 ACL2i PF GEN Line Terminal Card
TA 21513 Optical Line Terminal Repeater 2-8 M, 1300 nm LED MM/SM
TA 21516 Optical Line Terminal Repeater 2-8 M, 1300 nm LASER SM
TC 21301 DM8 Multiplex Equipment, 75 ohm
TC 21710.01 TMS Adapter
TF 21090.09 Subrack 19″, (EMC), grey
TU 21122.5 Data Interface Unit (DIU) 48..64k V.11 10ch
TU 21125 Data Interface Unit (DIU) 48..64k with sync, X.21
TU 21236.10 Channel Unit (CU) 8ch E&M/uP: 2xe&m/vf

This represents a list of the most common elements Customers need, but please do contact us if there’s something specific you’d like us to seek out for you. Always happy to help!

Vero Trivolt PSU – ‘product of the month’

TRIVOLT AC/DC-converter Power Supply Unit

Manufacturer: Vero

Model Number: PK60A

Product Code: 116.010018J


60 to 120 Watt switched mode AC/DC plug-in power supply with three outputs in 3 U Eurocassettes for use in 19” subracks to IEC 60297-3.

  • 3 high stability outputs, all adjustable
  • √  Safety approvals to UL, cUL and EN 60950
  • CE marked for compliance to EMC and Low Voltage Directives
  • SENSE-operation (5V output)
  • Overvoltage protection (OVP)
  • Powerfail signal optional
  • No-load and short circuit proof
  • Coded H15 connector
  • VERO standardised pinning


  • nom. height: 3U
  • nom. width: 8H
  • nom. depth : 160mm
  • output power: 60W
  • voltage outputs:
    • V1: 5V/6A
    • V2: -12-15V/1A
    • V3: -12-15V/1A

To purchase, contact us.

Spares Solutions

Legacy Infrastructure Hardware Elements

Can we help you with sourcing any equipment or spare parts for old legacy or even new infrastructure systems?
Many customers are needing to keep systems and infrastructure maintained to prolong asset life. This is particularly important for ‘legacy’ equipment that is approved for use and very reliable but in many cases no longer manufactured.
So here’s the solution: speak to the team at YellowsBest about anything you need to source to keep your systems in operational service.

Equipment Types 

– telecommunications hardware infrastructure products
– technologies including optical transmission, PDH, SDH, C/DWDM, microwave radio, PMR / TETRA
– software solutions including OSS / NMS
– IT equipment including personal computers and server hardware
– ancillary equipment such as power supplies, filters, monitoring devices, consumables
– cabling, wiring looms and connectors

 Vendor Systems

– Alcatel / Lucent e.g. 1511 Max
– Apple e.g. PowerMac G5 / Pro
– Benning e.g. MCU1000
– Bosch e.g. DSK
– Brocade / Foundry e.g. 10G
– Ciena e.g. SM-A, CM-A
– Cisco e.g. ISR 4300 series
– ECI Telecom e.g. OPBFC
– Eltec e.g. AL 175 NT
– Ericsson e.g. OMS 846, 860, 870, 1600
– Ernitec e.g. M2504 M/2
– Extreme Networks e.g. Summit
– Keymile e.g. UMUX, UNEM, XMP1
– Huawei e.g. M1000
– IBM e.g. PS/2 Model 80
– Juniper e.g. SRX5400, EX3300
– GEC / Marconi e.g. SMA SDH
– MRV e.g. EM 316, 1600, 2003, 2004
– Newbridge e.g. MCP, CEB, TDS
– Nokia Telecommunications e.g. Dynanet PDH DM2 DB2 DN2, Synfonet SDH TSW0, NMS/10, NMS/100, DX220
– Nokia Siemens Networks (NSN e.g. Surpass HIG1100, HIE9200, HIQ8000 
– Nortel e.g. OTR, OCLD
– RAD e.g. Megaplex, ETX, ASMi, RADview
– Tellabs e.g. DM8, MX8
– Thomson e.g. Speed Touch
– Transmode e.g. MDU, OCU
– 3COM e.g. Baystack
Normally parts will be ‘2nd user’ working condition, where new items can no longer be sourced, but in some cases unused ‘last time buy’ surplus stocks or even remanufactured items can be supplied. 
Please check your services and solutions requirements. If there is anything you need, please contact us to discuss how we may be of assistance to your organisation.