Sender Restart Indicator



Intelligent Indicators

Sender Restart Indicator – when sloppy senders meet picky receivers

Do you know why the RTP header has a sequence number? It is incremented packet by packet and is used to detect packet loss. If your phone detects a gap in the increasing sequence, then it knows that packets were lost along the way.

But what if the sequence number suddenly jumps back to 0? Doesn’t sound like a big issue? Well, it can be and has caused huge customers to suffer from one‐way audio. The reason is that the RTP standard does not define what to do if the sequence number unexpectedly decreases. Due to this, your phone may decide not to play out audio from packets with “funny” sequence numbers. All packets arrive – still there is silence.

Voipfuture Qrystal calculates hundreds of metrics and indicators for every stream in the network and for every 5 seconds in real-time. One is called “Sender Restart”. When needed, it makes life a lot easier for operations engineers.


Take care,


SIA – more than a million calls per week



SIA – more than a million calls per week

Hi all,


In my last post about the SIA (SDP in ACK) I said that the problem doesn’t come up that often. The question remained open: What does “not that often” mean?

The screenshot shows two things. Firstly, the problem is minor in percentage terms. On the other hand: In this case, more than a million calls per week are affected.

If the problem is regionally concentrated, the operations team definitely should know about it.


Take care,


Webinar: Media KPIs

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Rohde & Schwarz and Voipfuture launch AVQA to address new requirements in the ATM market

R & S AVQA KPI Monitor

Press Release

Rohde & Schwarz and Voipfuture launch AVQA to address new requirements in the ATM market

In an exclusive partnership, Rohde & Schwarz and Voipfuture address needs for quality assurance in transition to IP networks

Munich/Hamburg, June 30, 2020 – Rohde & Schwarz and Voipfuture today announced the release of R&S AVQA, a ground-breaking monitoring solution for voice communications in air traffic management (ATM). The transition to IP created new market needs and opportunities, which gave rise to the collaboration between the two companies.

R&S AVQA stands for ATC Voice Quality Assurance and provides air traffic service providers (ANSP) with unique passive monitoring capabilities for ATM communications that covers signaling as well as media and radio transmission performance. Rohde & Schwarz teamed up with Voipfuture to create a unique solution for this important market. The development of R&S AVQA strongly benefited from the experience Voipfuture gained in over 10 years of Voice over IP (VoIP) monitoring in the telecommunications industry.

The solution is already deployed in a few ANSP networks assuring service quality. Typical use cases are monitoring quality and performance KPIs agreed on with WAN providers/carriers or the regular reporting of network quality towards the respective Civil Aviation Authority. An additional benefit is a reduced troubleshooting time by quickly identifying and localizing root causes of IP network problems such as misconfigured routers/switches or faulty fibers.

“We identified these market requirements early and entered into a partnership with Voipfuture,” Constantin von Reden, Vice President Market Segment ATC at Rohde & Schwarz, states. “Voipfuture stood out with their impressive technology and their experience. The Voipfuture team is very customer-oriented, which perfectly aligns with our approach to the market. We are very happy to work with them on the outstanding R&S AVQA product.”

“We are proud to provide our outstanding technology to this partnership,” says Eyal Ullert, Chief Sales Officer, Voipfuture. “Thanks to Rohde & Schwarz’ deep understanding of the needs of ANSPs, we managed to adopt our existing technology to the specific requirement in the ATM market.”

R&S AVQA is part of CERTIUM Analysis which includes leading test and measurement solutions for VoIP networks, radios, navigation and satellite. Rohde & Schwarz recently introduced CERTIUM, as a one-stop solution for the full lifecycle of an ATC system.

Voipfuture, a premium voice quality analytics vendor providing tools for assessing, aggregating, analyzing, and visualizing voice quality information, headquartered in Hamburg, Germany, brings years of experience in the domain of VoIP monitoring. Rohde & Schwarz with its partner Voipfuture make a significant contribution to safe, secure and efficient ATM.


Press contacts

Europe (headquarters):

Dennis-P. Merklinghaus

(phone: +49 89 4129 15671; email:

North America:

Tomas Berghall

(phone: +1 503 5239489; email:

Asia Pacific:

Wen Shi Tong

(phone: +65 6 307-0029; email:


Carsten Niepmann

(phone: +49 40 688 900 125; email:

About voipfuture


Voipfuture offers software solutions and services for monitoring the performance of voice communication. Our mission is to help mobile and fixed service providers, international carriers and enterprises provide premium voice services.


We develop and sell monitoring systems offering a precise view on the media and control plane to assess voice services in IP networks. Over the years we have gained unique experience in assessing, aggregating, analyzing, and visualizing voice quality information. We are experts in integrating high resolution troubleshooting information with Big Data analytics.


Voipfuture’s founders started business with one simple insight: The assumption “more bandwidth means more quality” is not true. At a time, when voice quality was invisible they created a system that allowed to look into the network in real-time.


In 2007, Voipfuture brought the first RTP monitoring solution to market. A lot of innovations and patents have arisen over the years, but the core commitment endured: Voipfuture’s dedication to customer experience.


Headquartered in Hamburg, Germany, Voipfuture is globally present with deployments in North and Latin America, Europe, Africa, Asia and Australia.


  • First integrated solution for SIP & RTP monitoring
  • First to provide fixed timeslicing technology
  • First hybrid probe (active & passive monitoring)
  • Unique aggregation solution providing quality for all relevant dimensions
  • Market-leading automatic root cause analysis & pattern matching
  • Business Intelligence transforming wealth of data into customized dashboards and visual reports
  • Patents/applications covering core technology, e.g. root cause analysis and call correlation
Data protection
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Data protection
We, VOIPFUTURE GmbH (Registered business address: Germany), would like to process personal information with external services. This is not necessary for the use of the website, but allows us to interact even more closely with them. If desired, please make a choice: