• verifiable centrally issued identifier printed on card and can be verified by inserting into any phone
• coin-like small physical tokens
• offline verification processes could be as simple as a distributed poster with whitelisted id's
• distributed and decentralized bootstrapping based on trust in accepted id's

A group of people decide to issue some simkojns by organizing a simkojn-party:

1. people are told to bring an unused simcard
2. all simcards are verified that their printed ID matches that which have been flashed upon them
3. all simcard ID's are written in a alphabetically sorted document
4. the document is printed out and goes around to all attendants
5. each person finds their simcard id in the list and writes their signature next to it
6. the document is copied so all attendants get a copy
7. meeting is over, everybody leaves with each a simcard and a poster with the issued ID's

Kim walks into a coffeeshop and orders a cop of coffee:

1. Kim: I'd like to pay with simkojn
2. Barista: its one simkojn for a coffee
3. Kim: here is a simkojn
   kim hands over a simkojn with ID=145b
4. Barista: thanks, let me just verify :-)
   barista looks at the poster and quickly finds 145b on the ordered list
5. Barista: thanks kim, have a great day
   barista puts the simcard in the register
6. Kim: you too, see ya

Kim walks into a coffeeshop and orders a cop of coffee:

1. Kim: I'd like to pay with simkojn
2. Barista: its one simkojn for a coffee
3. Kim: here is a simkojn
   kim hands over a simkojn with ID=170b
4. Barista: thanks, let me just verify :-)
   barista looks at the poster and can't find 170b on the ordered list
5. Barista: sorry kim, i can't take the simkojn as its not on my list of accepted serial numbers
6. Kim: hmm, thats odd i received it as payment in my barber shop and its on my poster
7. Barista: i guess you have a attended a simkojn party i didnt attend, would you be willing to drop by with two other people that attended that simkojn party plus a copy of the handed out poster?
8. Kim: sure!!, see you in 5 minutes
   Kim leaves and comes back with two people (Finn and Oscar) plus a piece of paper
9. Barista: can i see the poster and can you tell me about the simkojn-party?
   Barista receives the poster and verifies that 170b is indeed on the list
10. Kim, Finn, Oscar and Barista establishes trust in the mentioned simkojn-party and decides that the new poster will be valid in the coffeeshop
    They verify that the signature of Kim, Finn and Oscar indeed is on the printout.
    Futhermore a customer in the coffeeshop also verifies the list and locates his signature on it.

Simcards have the following interesting properties making it nice as a physical currency:

1. globally trusted ICCID number
   ICCID is printed on the simcard plus readable with a phone from memory on simcard.
   wikipedia says :
   "Each SIM is internationally identified by its integrated circuit card identifier (ICCID). Nowadays ICCID numbers are also used to identify eSIM profiles, not only physical SIM cards. ICCIDs are stored in the SIM cards and are also engraved or printed on the SIM card body during a process called personalisation. The ICCID is defined by the ITU-T recommendation E.118 as the primary account number.[19] Its layout is based on ISO/IEC 7812. According to E.118, the number can be up to 19 digits long, including a single check digit calculated using the Luhn algorithm. However, the GSM Phase 1[20] defined the ICCID length as an opaque data field, 10 octets (20 digits) in length, whose structure is specific to a mobile network operator."
2. "free" physical tokens.
   its easy to find simcards, they are in the trash, you get them sent to you for free
3. nice size
   simcards are about the size of a 25 øre . You can easily carry them in a wallet