Institute of Communications and Connected Systems


Online Seminar | Telephony - from circuit to packet switching

20 January 2021, 11:30 am–12:30 pm

Image of manual Telephone switching board

Andy Valdar, visiting Professor at UCL will leverage his vast and varied experience within the telecommunications industry to consider and reflect on technology development through many generations of circuit switching and then look to how past technology deployment can inform current and future transitions.

This event is free.

Event Information

Open to

All | UCL staff | UCL students






Robert Thompson – Institute of Communications and Connected Systems

Telephony - from circuit to packet switching

Historically, telephony has relied on circuit switching through the many generations of technology – manual, step-by-step (e.g. strowger), crossbar, reed-relay, and digital TDM. However, over the last few years Telcos have been investing in packet-switched replacements for their digital circuit-switched PSTN and mobile switching units.

This talk briefly considers what lessons can be taken from the earlier deployments of new technology in live telephony networks and how those lessons can be applied to the current transitions.

ICCS Chair

This session will be chaired by: Izzat Darwazeh

Attending the seminar 

The Seminar will be held on the Zoom platform. Details of how to access Zoom can be found on their website.

Please click this URL to join. Zoom Webinar
Webinar ID: 937 4220 9922
Password: Will be distributed to ICCS members, others are welcome to join and the password can be requested by email.

Request password

About the ICCS online seminar series

The ICCS seminar series is designed to bring together members of our community who are currently away from our home in Bloomsbury and distributed across the world. The Seminars are being curated to provide academic exploration and inspiration, offering insights into a range of topics surrounding communications and connected systems. Topics will either explore subjects close to the work of our academics or introduce wider concepts from experts in the global academic and industrial community.

If you wish to suggest a future topic or speaker please use the link below, speakers could be from academia, industry, within ICCS/UCL or from further a field.


The seminar will begin with a presentation aimed at a technical audience, but at a level that will be accessible to those from a range of engineering disciplines. Speakers have been asked to end their presentations with a technical challenge or delving deeper into the content to engage those more invested in the topic. 

The seminar series is designed to offer a compact exploration of ranging topics and is therefore short in format. The presentation will run for 15 - 30 minutes, followed by 15 minutes of questions.
 Suggest a topic or speaker

About the Speaker

Andy Valdar

Visiting Professor at UCL

Profile picture of Andy Valdar
Andy Valdar has had a wide-ranging career in telecoms, covering network strategy, planning, international standards, regulation, product management, as well as teaching and writing.    After 30 years working for British Telecom, including three years on secondment to the United Nations in India, he joined University College London in 1999 directing part-time MSc programmes.  Although now retired from UCL, he retains his Visiting Professor role and still lectures and supervises on a part-time basis.  Andy has authored four text books on telecoms, is a Director on the ITP Board, was Chairman of the ITP Journal’s Editorial Board for 15 years, and was President of FITCE Europe for three years. He continues to be a key-note speaker at international conferences.

Andy is a Fellow of the IET and ITP, and a Chartered Engineer.  He obtained Bachelor of Technology (Hons) Degree from Loughborough University in 1969 and MSc in Telecommunications Systems from the University of Essex in 1972.  In 2018 he received an award from the IET (previously IEE) celebrating his 50 years in the industry.