Hi,
I am considering to carry an APRS rig with me during my planned trips to OE/VB-001 and OE/TI-035. Now, what is best to use to
a) use national call for APRS SSID and CEPT-prefixed call in the comments field or
b) use CEPT-prefixed call for the SSID?
In this discussion, people suggest a).
Any opinions?
73 de Martin, DK3IT
As far as I know, b) is not possible because the AX.25 frame format that APRS uses only allows for 6 bytes for the callsign and 1 byte for the SSID (and flag bits).
Personally, I think including the prefixed call sign in the comment field (Mic-E status text etc.) is good enough. You’re probably including your GPS position anyway, making it possible to identify which country you are transmitting from. OK, on second thought, that could be a bit difficult while you’re on top of OE/TI-035 or OE/VB-001 
Interestingly, the Austrian “Amateurfunkverordnung” law frees Austrian hams from the usual requirement of suffixing their callsign with the visited district number or /P if they use APRS and also transmit their GPS position ([1] § 22 (2a)). However, it does not say anything about CEPT prefixes.
73, Manuel HB9DQM
[1] RIS - Amateurfunkverordnung - Bundesrecht konsolidiert, Fassung vom 28.01.2023
I think in APRS you keep your home call. where-ever you are. It’s a data-field rather than an announcement of you calling on RF. I don’t believe BNetza (or equivalent) will be decoding APRS signals.
So your APRS-ID will always be DK3IT as I understand it.
73 Ed.
hello martin,
for portable activities you should use:
DK3IT-7
for mobile activities you should use:
DK3IT-9
further details here:
http://www.aprs.org/aprs11/SSIDs.txt
it is not necessary to change your callsign to OE/DK3IT-7 if you use APRS in Austria (and I think it’s the same in all other countries …)!
73 martin, oe5reo
Have you found an official source that says so? I’ve been looking for it, but haven’t found any specific regulations that say it’s OK to leave out the CEPT prefix for APRS (not that most OMs would care 
).
I’ve never used a CEPT prefix on APRS.
Ahoi
Pom
APRS as well as DSTAR do not have room for a longer prefix. I do not think it matters and I use my home settings as my callsign without the prefix. If I transmit voice or cw, I obviously use the prefix but not on APRS. I dont think it is a legal issue.
Thanks everybody! So I will go with DK3IT-7 as the SSID and OE/DK3IT/P in the comment field.
A bit academic really, none of the APRS equipped radios I’ve had will accept more than 6 characters for the callsign, and then only A-Z and 0-9 so not possible to add a CEPT / prefix. As you have decided just add the info in the comments field is the way to go.