Mobile or Portable?

Amateur radio callsign suffixes

Introduction and Approach

This discussion is regarding terms of the UK Amateur Radio Licence. Unfortunately this document is rather unclear and difficult to interpret on some issues. I was motivated to write this because I have been challenged on my use of the mobile suffix while on a summit and I have been confused by a station reporting to be portable when walking. In this article I try to make sense of determining whether one is operating mobile or portable.

There seem to be two approaches to defining the correct suffix to use. One is based on tradition and guessing what the other station might think you mean. The other is to use the definition in the licence and its notes. The problem with the first approach should be clear: you do not know how the remote operator will interpret you. All UK radio amateurs have a document which defines these suffixes. This is the only common standard and the only one therefore that should be used, even if it is not a very good one or you personally dislike it. You may think a traditional interpretation is more easily understood but that is not the case in general. It may be by people who gained their licence at the same time as you but new operators who have read their licence will not know what you mean.

I hope I have persuaded you that the correct approach is to follow the usage defined in the licence. The first thing we must do then is to read it! It is amazing how many radio amateurs seem not to have read the document that defines their hobby, or alternatively chose to ignore all updates since their licence was first issued. Reading it will not solve all problems but it is a good start.


Let us then look at the licence to see how it defines the situations in which you should use /M and /P. Section identifiers refer to the licence.

In "Notes to the licence":
(d) When operating at locations other than the Main Station Address, it is recommended that
the following suffixes be used:

    I. If the Licensee operates the Radio Equipment at an Alternative Address, the
       Licensee may use the suffix “/A” with the Callsign;
    II. If the Licensee operates the Radio Equipment at a Temporary Location, the Licensee
        may use the suffix “/P” with the Callsign;
    III. If the Licensee operates the Radio Equipment from a Mobile location, the Licensee
         may use the suffix “/M” with the Callsign;
We see that the choice of suffix depends only on the "location" of the equipment. Another important point is that these suffixes are only "recommended". You "may use" them, or not.


You are portable if at a temporary location. (by (d)(ii))
(jj) “Temporary Location” means a fixed location in the United Kingdom which is not
the Main Station Address or an Alternative Address;
Unfortunately "fixed location" is not defined. Some interpretations I have come across are:
  1. The station is physically fixed to the ground. This could be because of pegging a mast into the ground or connecting to shore power.[1]
  2. The station does not move for the period of operation. For example, a parked car or person sitting with handheld. Note I did not define "period of operation".
  3. The station remains within some defined area. This includes situations in the last definition but adds things like walking around in the region of a mountain top.

I cannot tell you which of these, if any, is officially correct, but I make some recommendations below.


17(1)(x) “Mobile” means the Radio Equipment is located in the United Kingdom:
    I. in or on any vehicle or conveyance;
    II. on the person of the Licensee where the Licensee is a pedestrian; or
    III. on any Vessel on Inland Waters;
This seems clear enough.


Let us now return to the question, "Am I mobile or portable?". We have seen the definitions of each and can note that they are not exclusive. That is, you can be portable and mobile at the same time! For example, if you are anchored in inland waters I would consider that to be a fixed location. The same goes for a car that has deployed a mast on the ground. According to the licence, I could sign as MM0HAI/M/P (or MM0HAI/P/M) in these circumstances.

Examples and Recommendation

The suffixes are optional. I suggest using them if you think they will be useful. I think this is almost always the case, so suggest you use them by default.

We have seen that within the licence terms there is some room for interpretation. It makes sense to chose the interpretation that best communicates the situation of the station.

I recommend:

  1. Use definition 1 of fixed location, unless circumstances make it more useful to use another. (See examples)
  2. Use at most one of /P and /M. This is in accordance with normal practice. Using more than one is likely to confuse.
  3. When both mobile and portable, chose based on your ability to operate the equipment and the affect your situation may have on your signal. This, I suspect, is the most useful information you could communicate in the suffix. Generally, if you are both mobile and portable then use mobile.


Situation Suffix Justification
On summit, using handheld radio on trig point /M In this situation, you have your hands full: logging is difficult and the antenna will be flapping around. You may be delayed in responding to an over because you need to stand up to get the aerial high enough and sit down to write or get a Mars bar out your rucksac.
Walking around a summit /M As above and your signal may vary with position.
Sitting in car, antenna pegged to ground. /P You are physically fixed, so certainly qualify for /P. You don't need to worry about effects of moving, e.g. changing signal, distraction, so /M not helpful.
Sitting in car, not fixed to ground (antenna on car only). Intention to remain at same location for some time. /P You can get comfortable, get log book out and generally forget about moving.
Sitting in car, not fixed to ground (antenna on car only). Likely to need to move at short notice /M May be affected by mobile issues and can't get too comfortable.
Unicycling on the deck of a vessel at sea, which is holding station. /M/MM/P It's far too good to stick to my one suffix suggestion.


Read the licence and follow it. The remaining ambiguity is chiefly that of defining what is meant by fixed location. Do this such as to provide the most useful information about your circumstances as they may affect the QSO.

Do not do something because everyone else does it. Do it because it is correct.

Historical Notes

I think much of the confusion arises from changes in the rules. M1MAJ says (sota):
Way back in the days before BR68, the standard licence did not permit operation from a motor vehicle. You needed to obtain (and pay for) a separate licence for that (just as you once needed a separate licence to have a broadcast radio in a car). That licence specified the /M suffix, which wasn't mentioned at all in the ordinary licence. Self-contained equipment that could be carried was much less common in those days, but such operation was possible, and legal under an ordinary licence, but could only be under a /P suffix. BR68 changed all that several decades ago, but the myth that /M means motor vehicle (only) has persisted to this day.
Brian, G8ADD says (sota):
I have my first licence issued in 1964 put away so safely that I can't find it! This is from a re-issue in 1977:
9.(1)(b) at the temporary premises the suffix "/A" shall be added to
the callsign.
9.(1)(c) at the temporary location or as a pedestrian the suffix "/P"
shall be added to the callsign.
9.(1)(d) in or on a vehicle or vessel the suffix "/M" shall be added
to the callsign.
9.(4) When the station is used at the temporary premises or location,
the address of the temporary premises or location shall be sent at the
beginning and end of the establishment of communication with each
separate amateur station, or at intervals of 15 minutes, whichever is
more frequent.
That is how it used to be, and I can add that we puzzled long and hard about exactly what 9.(4) meant!
Geoff, G6MZX replies with:
And that is rightly or wrongly the way that I interprit it now
So there you have another idea. Ignore your licence and just do what the 1977 one says instead.


  1. If you think the mobile / portable issue is bad enough, don't get me started on yachting situations. If you are tied up in a marina, are you /A, /M, /P or should you just make something up / forget about the whole mess?

Please send comments and corrections to mm0hai @ this domain.
© 2011