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ISDN Experts in Germany

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Hire experts who keep ISDN lines, PBX setups, PRI and BRI access, and migration paths to SIP or VoIP running cleanly. Get fast, precise matching with vetted, available freelancers.

Meet FRATCH Experts in Germany, who have recently used ISDN

Verified expert

Daniel Knirsch

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Project planning and implementation of a 95 kWp PV system

Freiburg im Breisgau
Daniel Knirsch

Last position:

Project planning and implementation of a 95 kWp PV system at Asset management company

  • Analysis of technical and economic feasibility
  • Creation of a detailed project plan including time and resource management
  • Requesting and evaluating offers, selecting components, and managing suppliers
  • Coordination of all involved trades (e.g. electricians, installation companies)
  • Monitoring the construction work and ensuring deadlines, budgets, and quality standards are met
  • Acceptance and commissioning of the PV system including documentation
  • After project completion: optimizing monitoring and supporting grid connection
Verified expert

Nick Reichardt

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IT Onsite Support

Berlin
Nick Reichardt

Last position:

IT Onside Support at Public Administration

  • Mobile Device Management (MDM) for iOS devices (iPads, iPhones)
  • Management, configuration and rollout of policies, apps and security measures
  • eSIM setup & management as well as management of mobile plans and contracts
  • User management (create, block, delete) in the SecurePIM security solution
  • Device registration, preparation and setup of devices with Windows 10/11 and peripherals
  • 1st & 2nd level support and handling of IT requests via the ticket system
  • Troubleshooting, fault isolation and repair of devices
  • Creating and maintaining guides, training new users and handling user questions
Verified expert

Mustafa Kederoglu

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Senior Network Design and Engineer

Frankfurt
Mustafa Kederoglu

Last position:

Senior Network Design and Engineer at Helaba

  • Designed and specified the technical network integration of a new business-critical application system (MUREX) in the capital markets area in a complex interface and outsourcing environment.

  • Created component specifications, a catalog of measures and an implementation plan.

  • Ensured proper integration of the developed results in line with the bank’s framework: IT compliance, IT security, change and release management.

  • Selected and integrated a new service provider for the bank; moved critical bank applications to the provider.

  • Designed, implemented and supported the new Cisco network and Fortinet security setup at the service provider data center.

  • Acted as technical interface between the bank, service providers and consulting partners.

  • Supported and further developed the network and security infrastructure (clients, servers, networks); performed error analysis and implemented solutions within agreed service levels.

  • Analyzed and diagnosed all security and network failures, glitches and malfunctions.

  • Initiated continuous improvements to ensure efficient resource use and acceptable response times for users.

  • Provided network support in a financial services organization and prepared operational changes on production banking network infrastructure for both large and small projects within strict change management discipline.

  • Designed, defined, tested, governed and improved engineering standards.

  • Performed the role of network architect for medium to large projects involving team resources.

Verified expert

Jürgen Kasch

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Management Consultant · Interim Manager, Cloud & IT Service Management (freelance)

Friedberg
Jürgen Kasch

Last position:

Interim Management / Business Succession – Process Analysis & Stakeholder Management

As part of the preparation and operational support of a business succession:

  • Company analysis: Analysis of the overall economic, organizational and structural situation (current state, strengths/weaknesses, risk potentials)
  • Process analysis: Recording and documentation of all relevant business processes (BPMN, UML) in the areas of management, finance, procurement, sales and operations
  • Process optimization: Identification of weaknesses and inefficiencies, development and operational implementation of improvement measures
  • Stakeholder management: Identification and analysis of all relevant internal and external stakeholders; structured communication and coordination with previous and future owners, shareholders and employees
  • Change management: Supporting the workforce and management through the handover process; building acceptance and trust among all participants
  • Governance & documentation: Creation and handover of structured operation manuals, process documentation and organizational handbook for the new business owner
  • Risk & vulnerability analysis: Assessment of operational and strategic risks in the handover process and development of recommended actions
  • Operational support: Interim takeover of leadership tasks; ensuring business continuity during the transition phase
Verified expert

Christoph Reiche

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IT Consultant

Augsburg
Christoph Reiche

Last position:

IT Consultant at Augusta Solutions

  • Successfully certified as Professional Scrum Master (PSM I)
  • Further training in AI trends, prompt engineering, and tools (ComfyUI, SD3.5, Flux, Loras)
  • Market analysis for the strategic realignment of the service portfolio
Verified expert

Dirk Werner

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CX & Service Transformation for Scaling Companies | Ex-Site Director | 25+ Years of Leadership

Erfurt
Dirk Werner

Last position:

Senior Consultant, CX, C-Sat, Customer Value Management at ojuto GmbH

  • Customer service reorganization at DCS Digital Charging Solutions, Munich

  • Management of nearshore service providers

  • Implementation of scorecard, quality management and CSAT definitions, customer loyalty

  • Customer service reorganization strategy at TWS Total Webhosting Solutions Group, Amsterdam

  • Brand consolidation

  • Webhosting mass market customer service strategy

  • Quality management and CSAT management definition, upselling

  • Provider strategy for nearshore customer service, RFP process at Advanzia Bank, Luxembourg

  • Definition of upsell campaigns for business customers from ISDN to NGN (VoIP) at 1&1 Versatel GmbH

  • Customer approach, migration conditions, order entry, service delivery, end-to-end processes, customer communication

  • Definition of customer service processes (telco, mass market, use cases) at E.ON Broadband, Avacon Connect GmbH, Berlin and Sarstedt

  • Order entry, field sales processes, commission accounting, CRM system requirements (MS Dynamics), service provider management

  • Definition of service sheets for phone and written contacts (skill definition, forecasting process, SL measurement, quality measurement, scorecard, bonus-malus) at Lechwerke (LEW), Augsburg

  • Support in the tender process for selecting service providers

Verified expert

Fritz Rathjen

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Concept development and project support for a VoIP-UCC telecommunications solution

Pfaffenhofen an der Ilm
Fritz Rathjen

Last position:

Concept development and project support for a VoIP-UCC telecommunications solution at Nationwide eye clinic network

  • As-is analysis of the existing heterogeneous telecommunications infrastructure (128 locations)
  • Requirements analysis for call center solution and VoIP / Unified Collaboration and Communication services
  • Creation of a solution proposal and a technical concept
  • Tendering for the new services
  • Contract negotiations
  • Support during the pilot phase
Verified expert

David Bleyer

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Acting Partner

Blieskastel
David Bleyer

Last position:

Acting Partner at Bliestal Consulting UG

  • Redesigning cablewise infrastructure with CAT 8.1 keystones, measuring the speed and quality of the new installation with Pockethernet, documentation at a local saddlery
  • CAT 8.1 installation and building a data center, site linking, VPN and VLAN configuration for a local car dealership, implementation of IT-Security standards like virus protection (G Data) and firewalling (OPNSense)
  • Relocation of a tax office with redesign of the IT infrastructure, virus protection (G Data) and backup solutions (QNAP)
  • Planning, conception and implementation of an inhouse data center, BSI-compliant for commercial laundry (including Proxmox-based virtualization of existing infrastructures, QNAP, G Data, OPNSense, APC)
  • Implementation and conception of security solutions in the SME sector
  • Collaboration on the IT-security concept for the Bremen network of authorities (in the dLAN network)
  • Creation of IT-security concept VOIS (modules MESO, KFZ/iKFZ) including audit preparation for KBA
  • Expansion of the IT-security concept for the online service for electronic residence registration (eWA) to include use as an eFA (one-for-all) service (nationwide)
  • Expansion of the IT-security concept to include modules wos & wvp
  • Concept development for the implementation of DIN SPEC 27076 at MSEs and SMEs
  • Creation and evaluation of emergency concepts
  • Creation and evaluation of response actions and BCM plans
  • Assessment of existing business continuity management (ISO 22301)
  • Development of BCM strategy options
  • Conducting awareness training
Verified expert

Luca Pacor

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ERP Program Manager

Hofheim in Unterfranken
Luca Pacor

Last position:

ERP Program Manager at Fiserv

  • The client is undergoing a comprehensive transformation. All SAP ECC landscapes worldwide are being migrated to SAP S/4HANA, with the goal of introducing a global standard template.

  • The program also includes the migration and modernization initiative "RISE with SAP", which may involve migrating selected country installations to the SAP Private Cloud.

  • On the stakeholder side, the program's reporting line extends up to the company's board and the implementation partner's board.

  • Fiserv Germany's ERP landscape currently includes several non-standard SAP tools and applications that extend the ECC environment's functionality and often integrate with downstream systems. As part of the move to SAP S/4HANA, it is essential to assess the core functionality, integration points, and future viability of these applications to determine their alignment with the target architecture.

  • The focus of the role is to provide expert advice and assessment to define the scope, strategy, and roadmap for migrating Fiserv Germany's SAP ECC system to SAP S/4HANA.

  • SAP's recommended best practices are followed, and a structured approach is used to ensure a smooth transition with minimal disruption while maximizing business value.

  • This assessment forms the basis for a successful SAP S/4HANA transformation, ensuring alignment with industry best practices, regulatory compliance, and future scalability.

  • Migration strategy definition – evaluating available transition approaches based on business objectives, technical feasibility, and SAP best practices.

  • Technical readiness assessment – conducting a system analysis to assess compatibility, custom code impact, data volume management, integration points, and infrastructure readiness for SAP S/4HANA.

  • Business process impact analysis – reviewing the latest business process documentation to define the scope and effort needed to implement required functions in SAP S/4HANA and identify process optimization opportunities.

  • Roadmap for non-SAP systems and applications – evaluating third-party and legacy applications for SAP S/4HANA integration and recommending consolidation, migration, or replacement strategies.

  • Deployment & implementation planning – defining a phased rollout approach, including project timelines, risk mitigation strategies, and key milestones aligned with business priorities.

  • The transformation is carried out in phases: the discovery phase leads to the explore phase, which then leads to the design phase and finally to the implementation phase.

  • Program management

  • Change management

  • Requirements management

  • Transition management

  • Stakeholder management

  • Risk management

  • Comprehensive coordination

Verified expert

Silvia Biedermann

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Consultant

Überlingen
Silvia Biedermann

Last position:

Business Consultant - Product Management Banking at Aareal Bank AG

  • Focus on EBICS optimization and further development of the customer’s internal EBICS application
  • Business and technical consulting for Aareal First Financial Solutions AG on products and applications of the EBICS standard in the areas of operations and further development, as well as project-related communication with external development partners and the product vendor to map the relevant optimizations on a technical level
  • In the role of business coordinator, consulting on content-related and regulatory requirements as well as technical prerequisites and needs, and consolidating these on a business level
  • Consulting on the use of EBICS formats
  • Review of the current EBICS standard for potential optimizations and further development
  • Analysis of the current state to identify further development potential and derive suitable recommendations for action, taking regulatory requirements into account
  • Carrying out EBICS tests during the project
  • Responsible on a business level for requirements management, and in this context capturing and documenting requirements for such tests
  • Design of a functional and long-term test management approach
  • Execution and evaluation of tests
  • Consulting on sustainable quality assurance and audits
  • Project languages: German and English
  • Tools/methods: MS Project, MS Office, MS Visio, TestRail, Confluence, Jira, Business Logics Bank Rechner, Business Logics test data generator, Business Logics banking tool, Business Logics test system, DBEAVER, Squirrel, Unix virtual machines, WinSCP, Kitty, PuTTY, various Aareal Bank products, online banking portal, Aareal Sign, core banking system, SAP Blue Eagle, SAP RE-FX, Aareon Wodis Sigma, Haufe Real Estate Wowinex, GAP Group Immotion, UTS Karthago, SAP IS-U/Waste, SIV kVASy, various EBICS clients
Verified expert

André Görst

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IT Consulting Project Management / Engineering Subproject Management

Berlin
André Görst

Last position:

IT Consulting Project Management / Engineering Subproject Management at T-Systems (on assignment for government agencies)

  • Projects for federal networks (NdB).
  • CR management, EoL change requests, design and documentation according to ITSCM.
  • Data center planning.
  • Project management and engineering subproject management.
  • Software development for virtual server environments according to BSI.
Verified expert

Andreas Zimmermann

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Senior IT Project Manager · Service Owner · ITSM · SIAM · Operating Models & Governance

München
Andreas Zimmermann

Last position:

ITSM Consultant at Industrial company / Global IT division

  • Designed and implemented a new user support tower organization as part of the global IT transformation initiative.
  • Created an operating and control model for the central service desk, including downstream support units (field service, VIP support, service points).
  • Performed a comprehensive as-is analysis of existing service desk and field service structures and developed a target architecture based on ITIL 4 and SIAM.
  • Defined roles, responsibilities, and governance mechanisms for internal IT and external providers.
  • Prepared the blueprint document Service Management & Governance Handbook (User Support) to standardize global service processes (incident, request, problem, change, knowledge, ITSCM, CSI).
  • Developed a KPI and SLA framework to measure service quality and performance in global user support.
  • Defined the reporting and review structure (operations meeting, service review meeting, management steering board).
  • Prepared RFP documents for the external tendering of L1/L2 support services, including definition of scope, governance model, process requirements, tool integration (ServiceNow), and KPI/SLA sets.
  • Supported procurement and legal departments in evaluating and negotiating vendor proposals and assisted in vendor selection and contract finalization.
  • Oversaw the handover to operational support, including knowledge transfer, training of provider teams, and establishment of a continuous improvement process (CSI).
  • Methods / framework / tools: ITIL 4 / ITSM, SIAM, IT4IT, ServiceNow, Jira, BPMN, operating model canvas, KPI & SLA design, governance & performance management
Verified expert

Reinhard Gefing

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IT Infrastructure / User Management

Raunheim
Reinhard Gefing

Last position:

IT Infrastructure / User Management at UMF – University Medical Center Frankfurt

  • User account management and creation in Active Directory
  • Group management and modification in Active Directory
  • Permission management on file servers
  • Exchange/Outlook support
  • VPN setup
  • System and product support: Windows 10, Windows 11, Office 2019, Office 365, Active Directory, TeamViewer, RSA VPN, Microsoft Teams, RSA Security Console, Deep Discovery Mail Inspector, ServiceNow, Macmon
Verified expert

Matthias Schmälzle

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Subproject Manager / Head of Monitoring

Achern
Matthias Schmälzle

Last position:

Subproject Manager / Head of Monitoring at IT service provider (Berlin/Kolbermoor)

  • Subproject Manager / Head of Monitoring for facility management and handling operational project parts as well as coordinating operations
  • CheckMK consulting: central monitoring infrastructure with CheckMK master and distributed CheckMK satellites
  • Implementation of advanced monitoring approaches, integration of new plugins and customization of the CheckMK agent
  • Graphic representation of performance metrics with InfluxDB and Grafana, creation of NagVis/Grafana templates and dashboards
  • Monitoring of Linux/UNIX/Windows systems and active components using CheckMK agents/MRPE as well as hardware monitoring via SNMP
  • Development of monitoring plugins based on Bash scripting
  • Inventory and cross-disciplinary analysis for application-specific monitoring
  • Concept design, testing and documentation for integrating CheckMK status messages and performance data into a higher-level umbrella system (Data Leak)
  • Technical and conceptual point of contact

Discover over 15,000 top freelancers

Statistics of experts using ISDN

Aggregated from the professional profiles of matched freelancers.

Experience

29 years

Position duration

2 years

Positions per freelancer

23

Top business areas

Information Technology, Project Management, Operations

Top industries

Information Technology, Telecommunication, Banking and Finance

Certification focus areas

Information Technology, Project Management, Product Development

Bachelor's degree or higher

72%

Master's degree or higher

36%

Doctorate

8%

Certifications per freelancer

3

Most common languages

German, English, French

Speak two or more languages

98%

Based on our profile pool as of 30 Aug 2026.

Daily rate distribution

0 4 8 12 16
<€480 €480-​640 €640-​800 €800-​960 €960-​1120 €1120+

The chart shows how the daily rates of freelancers in this technology in Germany are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows how many freelancers charge within that range.

Average rates of experts in Germany using ISDN

Rates are based on recent contracts and do not include FRATCH margin.

800
600
400
200
Rate comparison chart
Daily rate avg. 783 €

The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.

800
600
400
200
Rate comparison chart
Median rate 768 €

The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.

Calculated based on our freelancers’ daily rates as of 30 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.

About the technology

ISDN basics

ISDN, or Integrated Services Digital Network, is a digital telecom standard for voice, fax, data, and signaling over circuit-switched lines. It is still relevant in legacy office networks, alarm systems, payment terminals, and systems that depend on stable bearer channels and exact call control.

Common work

  • Maintain BRI and PRI lines and associated numbering plans
  • Configure PBXs, trunks, and switch settings
  • Troubleshoot call setup, echo, codec, and signaling issues
  • Support fax, modem, and special-purpose devices
  • Plan migration from ISDN to SIP or other IP telephony

Ecosystem and interfaces

Strong specialists know ISDN interfaces, NT and TE device roles, and signaling on basic and primary rate access. They also work with PBX systems, routers, gateways, and carrier handoff details where ISDN meets analog, IP, or private branch systems.

When companies bring help

Companies usually need freelance support when an old setup still carries real business traffic, when a carrier changes the line design, or when an office migration must not break fax and alarm services. In Germany, this often comes up in distributed branch networks and facilities that keep legacy telephony for compliance or operational reasons.

What good specialists do

Good professionals read line traces, isolate network-side versus customer-side faults, and document every change clearly. They understand call routing, D-channel signaling, device compatibility, and the risks of replacing ISDN too late or too fast.

Hiring signals

  • The phone system depends on legacy trunks or point-to-point links
  • Fax, alarm, or terminal devices still require ISDN behavior
  • Migration planning needs a clean cutover and fallback path
  • Internal teams know the business, but not the old telecom stack
  • Remote analysis is possible, but on-site work may be needed for wiring and handoff checks
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Frequently asked questions

Curious about ISDN? Here are the answers that come up again and again.

ISDN is used for digital voice, fax, data calls, and signaling over circuit-switched lines. Companies still rely on it for PBX connectivity, legacy branch office links, and devices that need a predictable bearer channel. It is especially common where old telecom equipment must keep working during a transition to IP.

ISDN carries calls over dedicated circuit-switched lines, while SIP and VoIP run over IP networks. ISDN is often preferred for legacy compatibility and stable call setup, but SIP is easier to scale and integrate with modern systems. A strong specialist can support both and plan the migration between them.

Yes, in most cases. ISDN work is closely tied to PBX configuration, trunk setup, numbering plans, and call routing. The best experts can also handle carriers, gateways, and the handover between the phone system and the line provider.

A strong ISDN specialist often knows PBX systems, telecom line testing, routing, and gateway configuration. Knowledge of SIP, VoIP, analog fallback, and network troubleshooting is also useful. For migration projects, documentation and change control matter as much as technical setup.

That depends on the task. A line fault or device replacement may need a focused specialist, while a migration from ISDN to SIP or a multi-site redesign needs deeper telecom experience and clean documentation. If the setup includes alarms or fax, choose someone who has handled those edge cases before.

ISDN can often be diagnosed remotely if the PBX, gateway, or carrier data is accessible. On-site support helps when wiring, handoff hardware, or physical line checks are involved. In Germany, many companies use a mix of both because legacy telecom rooms still need local verification.

Look for clear fault isolation, structured change logs, and practical experience with real line setups. A good ISDN professional explains whether the issue sits with the customer side, the carrier side, or the PBX. They should also show they can protect fax, alarms, and other legacy services during change.

The most common search terms are ISDN and the full name, Integrated Services Digital Network. In older documentation, people may also refer to BRI, PRI, or basic and primary rate access. A reliable specialist understands the naming and the technical differences behind each term.

The average hourly rate of freelancers in Germany who have used ISDN in their recent projects is 98 €, which corresponds to a daily rate of about 783 € based on an 8-hour working day.

Of the freelancers in Germany who have used ISDN in their recent projects, 72% hold at least a Bachelor's degree, 36% hold at least a Master's degree, and 8% hold a doctorate.

On average, freelancers in Germany who have used ISDN in their recent projects have 29 years of professional experience, with a single engagement typically lasting around 2 years.

The most common languages among freelancers in Germany who have used ISDN in their recent projects are German (100%), English (96%), and French (35%).

The most common industries among freelancers in Germany who have used ISDN in their recent projects are Information Technology (100%), Telecommunication (67%), and Banking and Finance (65%).

The most common business areas among freelancers in Germany who have used ISDN in their recent projects are Information Technology (98%), Project Management (92%), and Operations (81%).

Main locations of FRATCH Experts, who have recently used ISDN

Our freelancers and interim experts are at home across the DACH region — available on-site in the major business hubs or fully remote. Choose a location to discover matched specialists, local market insights and up-to-date availability.

Berlin Hamburg Munich Cologne Frankfurt Stuttgart Dusseldorf Leipzig Dortmund Essen Bremen Dresden Hanover Nuremberg

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