Public Safety Advocate: Network Interoperability?

This is the month of public safety’s “10-codes.” These 10-codes were used effectively for many years and are now being replaced with verbal commands. With better audio intelligibility and better networks, public safety has decided to give up 10-codes in favor of voice. The date of this week’s Advocate, 10-3, means “Stop Transmitting,” which I am ignoring as I write this column. Tomorrow’s date, 10-4, is the most recognized 10-code and means “OK” or “Affirmative.” Some 10-codes are used for things such as 10-36, “What time is it?” Others are used for incidents: 10-31, “Crime in progress,” 10-32, “Man with a gun,” 10-33, “This is an emergency,” and 10-38, used when stopping a suspicious vehicle. The complete list of 10-codes for General Purpose approved by APCO, and then differences in 10-codes between Norfolk, VA and Walnut Creek, CA, can be found here. Many of us grew up using 10-codes but I, for one, believe the move to plain and concise English has served the public-safety community well, especially since when you refer to the chart you will see that even with 10-codes there could be confusion about what someone really meant. 10-24 (Assignment Completed).

FirstNet Interoperability

As many of my readers know, I have been working with numerous groups and following others that are working toward linking Land Mobile Radio (LMR) networks with FirstNet (Built with AT&T), interoperability with Push-to-Talk (PTT), and interoperability among at least four PTT clients currently approved for use on FirstNet. This week I will broaden the discussion to include interoperability with other LTE-broadband networks. 

Last week was the deadline for filing a response to FCC Public Notice DA-19-902. “By this Public Notice, the Public Safety and Homeland Security Bureau (PSHSB) seeks comment on petitions for declaratory ruling and rulemaking filed by the Boulder Regional Emergency Telephone Service Authority (BRETSA).” The BRETSA document details why it believes other LTE-broadband networks should be permitted to, or FirstNet should be required to, accept interoperability from other network operators.

I did not respond to the FCC request because I have mixed feelings about this entire issue. On one hand, AT&T submitted a bid to be the exclusive provider of FirstNet services and priced its bid response accordingly. To fulfill the requirements of the contract, AT&T has been required to spend $billions of its own money to build out a Nationwide Public Safety Broadband Network (NPSBN). I believe if AT&T had known from the beginning that the winner would have to share customers with other network operators, its bid would have been substantially different. Further, no other major LTE network operator was a prime bidder on this RFP. During the first five years of the 25-year contract, AT&T has taken on additional obligations for delivering network coverage and signing up public-safety customers. Each of these items carries heavy penalties if AT&T fails to meet its obligations.

I can hear some readers asking, “Why does AT&T’s investment matter when we are talking about public-safety interoperability?” My answer is simple. If there is a need for discussions about network interoperability, and if network interoperability is deemed important to the public-safety community, the time for such discussions would be after AT&T has completed all tasks required by law within five years of the contract award. Then, if the FirstNet Authority deems AT&T has met all its obligations and is no longer subject to the fines spelled out in the RFP, that would probably be the appropriate time to broach the subject of network interoperability—Not before.

There are both operational and technical issues involved in providing network interoperability, starting with which revision of the 3GPP standards and what parts of each revision are used on a network. Today, new revisions contain several items that can be embraced or rejected by a network operator. This leads to differences between LTE networks even though they are all built to 3GPP standards. 

Each network operator has its own large and skilled staff to address various functions of its network. There are Radio Access Network (RAN) experts, backhaul experts, new site development and location experts, and a whole host of backend IT professionals handling different elements of the network including security, the core, and other properties of the network’s brains. As one would expect, there is often a difference in approach for how each network implements the various pieces and parts that constitute the entire network as well as the way in which one network is constructed and built out compared to another network. Linking two disparate networks, especially if they are to make use of a single, very secure, public-safety core as the law requires for FirstNet, is an extremely challenging undertaking.

To better understand this, let’s look back to the days when all the network operators were busy acquiring other networks or merging with them. Verizon was built by assembling many different telcos. I remember when the Air Force moved my son to Georgia and I wanted to add him to my Verizon account in California. At the time, Verizon was struggling with reconciling different billing systems from each region and I was told what I had requested was not possible since Georgia and California were on different billing systems. It took years to resolve this issue. 

I also remember the integration nightmares that had to be resolved. One dealt with a single cell site in Northern California. There were two cell systems on the tower, one for each of the two networks. One cell system was not compatible with the other and had to be replaced, which took time. I also remember vividly that during the merger rush in Southern California, it was discovered that one network was using T-1 connectivity and the other was using only copper pairs for point-to-point communications, thus data speeds varied greatly between locations. 

All these issues and more were resolved but doing so took time, money, and energy. There seems to be an assumption that since LTE is a 3GPP standard, it is compatible network-to-network. Since this is not always the case, I am suggesting that when and if network-to-network interoperability is deemed necessary, any decisions should be based on operational capabilities. In one example, I am told AT&T’s Kodiak PTT used on FirstNet and Verizon’s Kodiak PTT are different and not compatible. Providing network interoperability would not fix this issue. As the public-safety world blindly moves to Mission-Critical Push-to-Talk (MCPTT), I believe strongly in over-the-top PTT applications such as those offered by ESChat, Tango Tango, and others. Over-the-top PTT enables a Verizon, T-Mobile, or Sprint user to communicate with a FirstNet user by means of PTT. These are proven solutions for voice interoperability that are available today.

Texting is not an issue since texting between other networks and FirstNet works well. That leaves data and video service, which are certainly important. But even over FirstNet and other networks, applications are not standardized so coupling the networks would not necessarily result in data and video interoperability. Network interoperability may be a good goal sometime in the future, but there are many issues to be addressed. There are a variety of ways for non-FirstNet users to communicate with FirstNet users today that address many of the concerns being brought to the FCC’s attention. 

Band 14

I also feel strongly that authorizing access to public-safety Band 14 for more than one network operator would create more problems than it would solve. In the LMR world, frequency coordinators must be consulted when requesting additional radio channels or making changes to existing networks. These coordinators minimize chances of interference between two or more agencies. While this works most of the time, it is not foolproof and if there are interference issues, they are dealt with in good faith between the license holders. It is difficult to imagine sharing Band 14 and not running into interference, priority and pre-emption conflicts, and a host of other problems that would take time and money to resolve, if they could be resolved.

I believe the bottom line is that AT&T must be allowed to complete its five-year commitment to the FirstNet buildout before revisiting the network interoperability issue. If a network operator now sees its customers leaving after choosing not to take part in the RFP process and wants to fight back by offering access to FirstNet to keep them, such access should be determined based on operational concerns, not mandated on a technology level. The network complaining the most and stirring all this up was not a bidder and stated on the record that it had no interest in public-safety Band 14 since it did not need the spectrum. Yet once it saw some of its customers leaving for FirstNet, it decided it really did want to play in this market. 

How do you provide what some seem to think is needed in the way of LTE network interoperability and still enforce the requirements and penalties laid out in the RFP? It would be a tough choice and I think it should wait until after the FirstNet Authority determines whether AT&T has fully fulfilled its obligations under the terms of the agreement.

Winding Down

Congratulations to Chris Sambar, who has served as head of the AT&T FirstNet organization since 2017. Mr. Sambar is being promoted within AT&T and will hold the office of Executive Vice President. Jason Porter, who was most recently the Chief Data Officer (CDO) at AT&T and led the strategic planning organization of AT&T’s Technology Operations will be his successor. Mr. Porter has been with AT&T since 2002 and has served in a variety of roles within the company. 

I enjoyed the time I was able to spend with Mr. Sambar. He was driven to make certain the public-safety community received the best of everything from AT&T. The core of the FirstNet operation, headed by Jim Bugel, remains in place. Mr. Bugel replaced Stacey Black in the very early days of the Public Safety Alliance (PSA) and supported FirstNet from day one. AT&T has put together a winning team for its FirstNet endeavor and the progress that has been made in only a few short years speaks volumes about its dedication to the public-safety community. It appears FirstNet has been good for AT&T management and I am sure they will continue to be good for the public-safety community.

October is here already and the Atlantic Ocean looks like many witches’ caldrons coming to a boil. Hopefully, none will make landfall on the East Coast, but if they do, I am confident public safety and FirstNet will be prepared. Meanwhile, PG&E, the primary electric company in California, is instituting a program to turn off power in times of high fire danger. This is obviously a response to reports that some of the worst wildfires in California’s history have been ignited by downed electrical wires. 

While I no longer live in California, I am concerned about its citizens, especially the elderly who need dependable power for medical equipment that helps them breath and receive other necessary medical services, those who sleep with CPAPs for their breathing, and much more. It seems to me there has to be a better way to manage power than to simply cut it off for thousands of people in the area every time there is a red-flag warning. Some time ago, I read about a 5G application in development that would cut power to only a single leg of the power feed if a wire was downed, and it would do so before the wire hit the ground. I hope there has been progress on this because shutting off power to many seems to me to be an overreaction.

In Arizona, we have new law not to shut off power, but to keep it on. The two main power companies will no longer be permitted to cut power to customers who do not pay their bills during summer months when temperatures reach 100°-plus. This came about after a customer actually died a heat-related death after his/her power was turned off. This action seems better suited to the situation than the California initiative to allow power companies to cut power to all area citizens during red-flag alert days.

As an associate member of the International Association of Fire Chiefs (IAFC), I have read a lot of its information as well as information from the Western Chiefs Association. It is evident from what I have read that the entire fire community is actively exploring ways to better fight fire and other disasters that continue to grow in magnitude. My hat is off to these dedicated chiefs and their staffs for not waiting for the next set of emergences to find new and better ways to deal with these events. They are on the job each and every day.  

Until next week…10-24

Andrew M. Seybold, Sr.
©2019, Andrew Seybold, Inc 


6 Comments on "Public Safety Advocate: Network Interoperability?"

  1. Andy, First about interoperability. I agree that an over the top method will best serve all involved. I also believe that the O-Ran Alliance will develop a secure,peer to peer method for interoperability among carriers without sacrificing individual network security. Second, as for band 14 access by any other carrier, the successful bidder to build the NPSBN (FirstNet) should be the only carrier with access period. From a business perspective AT&T understood the value of band 14 to public safety and the value it added to the product (FirstNet by AT&T) that would entice the public safety community to switch to their offering. Now with the advent of HPUE (which is only permissible on band 14) and other developments in the pipeline, we hear the old familiar chant from others (namely Verizon) “We want in”. By granting them access, you decrease the value of the contract, and I did say contract that only allows use by AT&T and its FirstNet subscribers only. If some ill-advised court or other government agency intervenes and allows this to happen, we can anticipate a major lawsuit which only have a detrimental effect on all we have achieved to this point. Some need to remember that even though AT&T is the contractor building and marketing FirstNet, it is still an independent government agency created by congress.

  2. Ryan Poltermann | October 4, 2019 at 12:49 pm | Reply

    Hi Andrew,
    Interesting take! There’s some aspects that I feel need addressing. I was responsible for the Norfolk radio system design, and they haven’t used 10 codes in many years. This is easily verifiable, if you would like to. In addition, the Commonwealth of Virginia has had a Common Language Protocol since 2006. I’m also not sure how a billing issue approximately 15 years ago applies to today, and I’d like to understand how this applies to FirstNet.

    With respect to Band 14, not a single petition asked for direct interoperability on Band 14. What has been asked for is carrier-to-carrier interoperability, particularly in disaster scenarios. Hurricanes, tornadoes, and wildfires don’t care who owns what cell site or the fiber supporting the site. Carrier interoperability will be deployed in South Korea for public safety, so this isn’t a new or impossible concept. It will be interesting to see how that develops over time, as they’re further along in their deployment.

    While there are commercial filings, these are far less important than the opinions of those directly involved within public safety such as Boulder Regional Emergency Telephone Service Authority, Minnesota Department of Public Safety Emergency Communication Networks, and a police chief from Irving, Texas. There is not a single filing by public safety that supports a FirstNet-only approach.

    With respect to OTT PTT solutions, there are some good solutions out there, but they’re proprietary and may not necessarily have priority (particularly on other carriers). It also introduces fragmentation where OTT PTT vendor A isn’t interoperable to OTT PTT vendor B. An open standard is in the best interests of public safety, and that’s the whole reason that P25 and other standards exist.

    Randy brings up an interesting point about the O-RAN; Open-RAN documents aren’t publicly available without signing legal agreements, and it would be beneficial to know what impacts there will be for public safety. A minor correction on Randy’s statement is that HPUE is available besides Band 14; as an example Sprint has had it for 2.5 GHz starting about two and a half years ago and 5G NR also has some HPUE bands that are being developed (example being n77).


  3. Ryan first thanks for your post. To start out my first paragraph said “were used” not are used so I expressed the fact that the 10-codes are no longer used. I posted the URL of where I got my 10-code list and made a comment that even with a standard 10-code there were still confusing differences between some entities and I sited VA as one of them since they were listed. I know full well, as my readers also no that 10 codes are not longer used except in CB land.
    On to your other comments. I won’t disagree that OTT applications may be, at this point in time proprietary but so are Kodiak and others since no one has implemented the MCPTT standard and I don’t believe that it ever will be fully implemented.
    You comments about past issues with networks cooperating is interesting, I just reached into the past to show that the issues for total interoperability between networks has been an issue for a long time. In fact, if you go look at a site that lists compatible devices you will find that AT&T is more compatible with T-Mobile and Verizon is more compatible with Sprint, it just depends upon what parts of the 3GPP standard they implement.
    I did not mention Sprint and High power UEs since Sprint is not one of the networks which is lusting after FirstNet customers, and since, at this point of all of the networks which have public safety users in large number on them, AT&T (FirstNet) is the only one which can offer high power on band 14.
    Lastly your claim that no one wanted to share band 14 is not 100% correct, if you go back to Verizon’s announcement at APCO after the bid was awarded and read the press following that, you will see that they went after sharing band 14 and asked FirstNet Authority for a ruling which came back in favor of AT&T and FirstNet.
    Once again thanks for your response and if you have any issues with my comments we can continue to dialog here in public or between ourselves, your choice. Have a great week-end.

  4. Ryan Poltermann | October 5, 2019 at 11:46 am | Reply

    Hi Andrew,
    Happy to! I’ll reach out to you sometime next week. In the meantime, some things to clarify.

    With respect to MCPTT, that is already operational in South Korea: . It’s actually been in use since 2017.

    The topic at hand with the petitions isn’t device band capability (which is more a matter of physics than anything), it’s primarily about carriers working together at the network level. My statement about Band 14 was this (i.e. for DA-19-902): “With respect to Band 14, not a single petition asked for direct interoperability on Band 14.” This is accurate, even Verizon didn’t. In fact, the most interesting aspect of the Verizon petition is talking about Title III, but that’s a whole topic in itself. Band 14 discussions in my eyes distract from what was actually submitted, as it’s not a component of any of the petitions/comments.

    Have a great weekend, and look forward to chatting with you!

  5. Ryan,
    The Korea Telecom MCPTT deployment is not compliant to the 3GPP MCPTT standards. It does not adhere to the common air interface; therefore, it does not support multi-vendor interoperability. As such, an iOS based 3GPP compliant MCPTT client cannot communicate with the MCPTT server. It is my understanding that the KT MCPTT server, which was reported by ‘Urgent Communications’ to be from Samsung, only supports Samsung Android phones. Also missing from the KT MCPTT system are key features which differentiate 3GPP MCPTT from today’s Over the Top and Carrier integrated PTT offerings. These features include Direct Mode, eMBMS Multicast and iOPS. In addition, the KT MCPTT system does not support LMR interoperability, which is not detailed as part of the 3GPP MCPTT specification. I believe we all agree that LTE to LMR integration is a key element required for successful adoption of broadband PTT by public safety.
    FirstNet has promised that we will see MCPTT in 2019, though I suspect its initial release will be lacking in features and interoperability functions, and will not hold up against the more mature Carrier Integrated and Over the Top solutions in use by public safety today. Standby… time will soon tell.


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