MYSTERY CALLS
FIELD SERVICE MYSTERY CALLS
As an experienced provider of mystery calls, we support agencies, market researchers, and institutes in conducting covert test calls to gather valuable data and practical insights. We uncover weaknesses and problem areas in call interactions and help address them systematically. Our test calls actively contribute to improving service quality and deliver precise feedback to optimize your customer communication.

Foerster & Thelen – Germany’s No. 1 for field research
- Germany’s leading field service provider
- Expertise in Mystery Calling
- mehrere 1.000 Mystery-Checks pro Jahr
- More than 1,500 trained testers and callers nationwide
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OUR SERVICE PORTFOLIO AS THE LEADING MYSTERY CALLING DATA COLLECTOR:










Mystery calls implemented professionally
For agencies, market researchers and institutes
As a specialist in mystery calling, Foerster & Thelen Marktforschung Feldservice GmbH supports agencies and market research institutes in collecting test call data.
As an experienced partner, we offer you support with:
- Collection of relevant data on customer communication
- Identification of improvement potential
- Capture of customer satisfaction insights

Why Foerster & Thelen?
- Excellent data quality: Reliable, unambiguous data collection for well-founded decisions
- Fast evaluation: Prompt delivery of data for swift analysis
- Tailored solutions: Custom test calls designed exactly around your research needs

Foerster & Thelen: your partner for high-quality telephone mystery checks
Does your client want to ensure that the company’s telephone customer service meets the highest standards? Foerster and Thelen supports agencies, market researchers, and institutes in analyzing and optimizing the quality of customer communication through professional mystery calling.
How we can help you:
With covert test calls, our experienced testers check whether call center staff optimally deliver service, consultation, and presence. We simulate real inquiries to objectively assess whether quality standards are being met. This allows us to identify opportunities for improvement and help sustainably increase customer satisfaction.
Our approach – tailored and precise:
- Custom test scenarios: Together with you, we develop tests that fit the company’s requirements perfectly.
- Detailed checklists: Our trained testers work with clearly defined criteria covering waiting time, answer quality, friendliness and closing behaviour.
- Realistic enquiries: The tests are designed to blend into everyday call-centre operations and deliver authentic results.


What we review:
Our test callers can examine a wide range of aspects to comprehensively evaluate the quality of a customer service:
- Response time: How quickly is the call answered by an employee?
- Competence: Can the enquiry be answered directly and with expertise?
- Quality of answers: How precise and helpful are the employee’s answers?
- Individual support: Does the employee respond to the caller’s needs and prior knowledge?
- Friendliness and empathy: How friendly and attentive is the employee during the call?
- Closing behaviour: Does the employee actively work towards a positive close, for example by offering a solution, a product or further support?
- Initiative: Does the employee make an effort to fully resolve the request and provide additional helpful information?
- Call structure: Is the conversation clear, goal-oriented and professional?
- Adherence to standards: Are key requirements, such as addressing the caller by name or using defined phrasing, applied consistently?
Through this detailed review, you learn how well staff members are at closing customer inquiries while optimally leveraging potential sales opportunities.
The best data for your analysis:
Based on the results, we can help you develop concrete action and training recommendations to work specifically on your team’s strengths and weaknesses. This gives your staff valuable feedback, and your customer service is sustainably strengthened.
Check the quality of telephone customer contact now – with mystery calling from Foerster and Thelen.

CONTACT US NOW FOR YOUR FREE, NO-OBLIGATION QUOTE!
How mystery calling supports business success:
- Improved customer satisfaction: By identifying and specifically fixing weaknesses in telephone service, customers feel better understood and supported. That builds trust and strengthens loyalty to your company.
- Increased sales: A well-trained employee makes the most of sales potential – through cross-selling, up-selling or by closing an enquiry in a way that convinces the customer and builds long-term loyalty.
- Greater efficiency: Detailed test results let you invest in the right training instead of spreading resources thinly. That saves time and cost and keeps your team focused on the right levers.
- Positive brand image: Reliable, friendly and competent service leaves a lasting impression. An excellent reputation as a customer-focused company can attract new customers and retain existing ones.
- Measurable success: Systematic review and optimisation of service processes make progress visible. You can track the direct impact on customer ratings, repeat-purchase rates and sales growth.
- Detailed, objective data collection: We capture data against clearly defined criteria, from response times and conversation management to sales and closing orientation. Reports are clear and practical, so you can derive actions you can implement immediately.

With Foerster & Thelen as an experienced field service provider, agencies and market research institutes receive precise and reliable data on the quality of customer interactions, forming a solid foundation for developing concrete optimization approaches for their clients.
How mystery calling supports business success:
Our mystery projects have already helped optimize customer service in numerous industries, including:
- Marktforschung
- Public institutions
- Banks and insurance
- Tourism and travel
- Advertising and communications agencies
- Einzelhandel
- Hotels, restaurants and hospitality
- Telekommunikation
Thanks to this cross-industry experience, we are able to offer tailored solutions for a wide range of requirements.
About Foerster & Thelen Marktforschung GmbH
Foerster & Thelen Marktforschung GmbH is one of the leading providers of field services in the area of market and opinion research in Germany. Since its founding in 1977, the company has developed into one of the largest independent providers of data collection services and offers comprehensive field services both nationally and internationally.
With an experienced team, the company conducts approximately 1.5 million interviews annually, covering a wide range of methods, including CATI, CAWI, CLT, POS and social science surveys, as well as mystery checks and home-use tests. Over 1,500 interviewers from across Germany ensure that even hard-to-reach target groups can be effectively surveyed.
Foerster & Thelen Marktforschung GmbH is distinguished by its high capacity and flexibility, making it a preferred partner for large-scale research projects. The company specializes in conducting complex studies with the highest demands on data quality, in both B2B and B2C sectors.
The services offered include face-to-face surveys, mystery research, mobile data collection in retail, online surveys, and mixed-mode projects, in which various collection methods are combined. With over 100 web-enabled CATI stations and centrally located test studios, Foerster & Thelen offers a modern infrastructure that creates ideal conditions for qualitative market research.
Through the high quality and flexibility of its services, Foerster & Thelen Marktforschung Feldservice GmbH has earned the trust of numerous renowned clients. They value the reliable and straightforward collaboration as well as the ability to deliver high-quality results even under challenging conditions.
As an experienced provider in empirical research, Foerster & Thelen places great emphasis on strict quality standards and continuous innovation, making the company an indispensable partner for organizations that rely on precise and well-founded analyses.
WOULD YOU LIKE INDIVIDUAL CONSULTING FOR YOUR PROJECT?CONTACT US NOW FOR YOUR FREE, NO-OBLIGATION QUOTE!
Comprehensive project planning and delivery
Foerster & Thelen handles the complete planning and coordination of your projects – from recruiting and training test callers to technical execution and comprehensive quality control. You receive regular updates on project progress and always have a dedicated contact person who supports you throughout the entire process.
Through our many years of experience and our broad range of methods, we can implement even complex study designs. If you have special requirements, please contact us – we will develop customized solutions for your mystery calls together with you and ensure that all your specifications are professionally implemented.

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Get in touch and benefit from our expertise in mystery shopping projects

Marcus Mattern
Head of POS
FAQ – Frequently asked questions about mystery calling
Mystery calls, also referred to as test calls or covert calls, are targeted test calls in which a trained tester simulates a predefined scenario. The caller evaluates the quality of telephone customer contact according to established criteria such as accessibility, friendliness, and professional competence. The goal is to gather objective information that contributes to improving service quality and customer orientation.
MORE INFORMATION AND CONTACT:
Trained testers conduct test calls in our call center based on previously developed, individually tailored test scenarios and checklists. These scenarios are specifically adapted to the requirements and objectives of the respective company. During the call, aspects such as wait time, friendliness, quality of responses, and closing behavior are evaluated. After the test is completed, a detailed analysis can be conducted to help you contribute to optimizing telephone customer contact.
The criteria can be adapted according to individual requirements.
Review criteria include, for example:
- Accessibility: How quickly is the call answered?
- Greeting and name usage: Is the customer greeted warmly and addressed correctly?
- Professional competence: Is the staff member knowledgeable and able to provide competent answers?
- Engagement and service orientation: Does the staff member show genuine interest in the inquiry and offer solutions?
- Active listening: Is the caller treated attentively and empathetically?
- Closing behavior: Is the call concluded professionally?
Test calls provide valuable insights into the actual quality of your telephone customer communication. They can uncover weaknesses that affect both customer satisfaction and employee performance. By having tests conducted regularly, you can continuously improve the quality of your customer service and ensure that your team always works in accordance with company guidelines and quality standards.
Unlike mystery emails, in which testers send inquiries via email, and mystery chats, in which they use digital channels such as live chats, mystery calls refer to telephone test calls. While test calls directly evaluate the conversational behavior of staff on the phone, mystery emails and mystery chats enable an analysis of written customer contact.
The main goal is to measure and optimize the quality of telephone customer contact. This includes not only technical accessibility, but also the friendliness, professional competence, and service orientation of staff. By improving these areas, you increase customer satisfaction, optimize customer service, and ultimately enhance the company’s success.
Our calls are conducted by trained testers who are specifically prepared for the needs of the respective company. These testers have extensive experience and are able to provide objective and detailed evaluations. If needed, the tested staff receive direct feedback to identify and implement improvement potential.
The frequency of tests depends on the individual needs of the company. Many companies conduct regular tests to ensure that quality standards are continuously maintained. Depending on company size and complexity, it may be useful to conduct mystery calls at certain intervals or at special times.
You can contact us at any time without obligation to receive further information or commission a project. Our experienced team will be happy to advise you, develop an individual concept for your tests, and ensure that the covert calls are seamlessly integrated into your existing processes.
Yes, covert test calls are permitted in Germany, provided they are organized transparently, proportionately, and in compliance with data protection regulations. However, certain legal requirements must be met:
Consent of those involvedCompanies whose employees are being tested must be informed in advance that test calls may take place as part of quality assurance measures. General consent from the company is required. However, individual employees do not need to be informed in advance about specific calls.
Data protectionThe General Data Protection Regulation (GDPR) must be strictly complied with. This means, in particular, that recorded conversations may only be stored or evaluated with the explicit consent of the persons concerned.
Employment lawTest calls must not constitute unlawful employee surveillance. They must be aimed at quality assurance and must not be misused for individual performance monitoring.



