diff --git a/pySim-shell.py b/pySim-shell.py
index 4d4f2e23..b48abc74 100755
--- a/pySim-shell.py
+++ b/pySim-shell.py
@@ -137,11 +137,6 @@ def init_card(sl):
     # Create runtime state with card profile
     rs = RuntimeState(card, profile)
 
-    # FIXME: This is an GSM-R related file, it needs to be added throughout,
-    # the profile. At the moment we add it for all cards, this won't hurt,
-    # but regular SIM and UICC will not have it and fail to select it.
-    rs.mf.add_file(DF_EIRENE())
-
     CardModel.apply_matching_models(scc, rs)
 
     # inform the transport that we can do context-specific SW interpretation
diff --git a/pySim-trace.py b/pySim-trace.py
index 4c8696d4..ba1568cf 100755
--- a/pySim-trace.py
+++ b/pySim-trace.py
@@ -11,7 +11,7 @@ from pySim.filesystem import RuntimeState
 from pySim.cards import UiccCardBase
 from pySim.commands import SimCardCommands
 from pySim.profile import CardProfile
-from pySim.ts_102_221 import CardProfileUICCSIM
+from pySim.ts_102_221 import CardProfileUICC
 from pySim.ts_31_102 import CardApplicationUSIM
 from pySim.ts_31_103 import CardApplicationISIM
 from pySim.transport import LinkBase
@@ -70,8 +70,9 @@ class DummySimLink(LinkBase):
 
 class Tracer:
     def __init__(self, **kwargs):
-        # we assume a generic SIM + UICC + USIM + ISIM card
-        profile = CardProfileUICCSIM()
+        # we assume a generic UICC profile; as all APDUs return 9000 in DummySimLink above,
+        # all CardProfileAddon (including SIM) will probe successful.
+        profile = CardProfileUICC()
         profile.add_application(CardApplicationUSIM())
         profile.add_application(CardApplicationISIM())
         scc = SimCardCommands(transport=DummySimLink())
diff --git a/pySim/cdma_ruim.py b/pySim/cdma_ruim.py
index 8b664902..b254403f 100644
--- a/pySim/cdma_ruim.py
+++ b/pySim/cdma_ruim.py
@@ -22,7 +22,7 @@ import enum
 from pySim.utils import *
 from pySim.filesystem import *
 from pySim.profile import match_ruim
-from pySim.profile import CardProfile
+from pySim.profile import CardProfile, CardProfileAddon
 from pySim.ts_51_011 import CardProfileSIM
 from pySim.ts_51_011 import DF_TELECOM, DF_GSM
 from pySim.ts_51_011 import EF_ServiceTable
@@ -191,3 +191,14 @@ class CardProfileRUIM(CardProfile):
     @staticmethod
     def match_with_card(scc: SimCardCommands) -> bool:
         return match_ruim(scc)
+
+class AddonRUIM(CardProfileAddon):
+    """An Addon that can be found on on a combined SIM + RUIM or UICC + RUIM to support CDMA."""
+    def __init__(self):
+        files = [
+            DF_CDMA()
+        ]
+        super().__init__('RUIM', desc='CDMA RUIM', files_in_mf=files)
+
+    def probe(self, card: 'CardBase') -> bool:
+        return card.file_exists(self.files_in_mf[0].fid)
diff --git a/pySim/filesystem.py b/pySim/filesystem.py
index 22ff60dc..cb3b403e 100644
--- a/pySim/filesystem.py
+++ b/pySim/filesystem.py
@@ -1307,6 +1307,16 @@ class RuntimeState:
         self.card.set_apdu_parameter(
             cla=self.profile.cla, sel_ctrl=self.profile.sel_ctrl)
 
+        for addon_cls in self.profile.addons:
+            addon = addon_cls()
+            if addon.probe(self.card):
+                print("Detected %s Add-on \"%s\"" % (self.profile, addon))
+                for f in addon.files_in_mf:
+                    self.mf.add_file(f)
+
+        # go back to MF before the next steps (addon probing might have changed DF)
+        self.card._scc.select_file('3F00')
+
         # add application ADFs + MF-files from profile
         apps = self._match_applications()
         for a in apps:
diff --git a/pySim/gsm_r.py b/pySim/gsm_r.py
index 389a8cb8..cd111d68 100644
--- a/pySim/gsm_r.py
+++ b/pySim/gsm_r.py
@@ -35,8 +35,8 @@ from construct import Optional as COptional
 from pySim.construct import *
 import enum
 
+from pySim.profile import CardProfileAddon
 from pySim.filesystem import *
-import pySim.ts_102_221
 import pySim.ts_51_011
 
 ######################################################################
@@ -362,3 +362,15 @@ class DF_EIRENE(CardDF):
                            desc='Free Number Call Type 0 and 8'),
         ]
         self.add_files(files)
+
+
+class AddonGSMR(CardProfileAddon):
+    """An Addon that can be found on either classic GSM SIM or on UICC to support GSM-R."""
+    def __init__(self):
+        files = [
+            DF_EIRENE()
+        ]
+        super().__init__('GSM-R', desc='Railway GSM', files_in_mf=files)
+
+    def probe(self, card: 'CardBase') -> bool:
+        return card.file_exists(self.files_in_mf[0].fid)
diff --git a/pySim/profile.py b/pySim/profile.py
index e464e1f9..0d09e81b 100644
--- a/pySim/profile.py
+++ b/pySim/profile.py
@@ -88,6 +88,7 @@ class CardProfile:
                 shell_cmdsets : List of cmd2 shell command sets of profile-specific commands
                 cla : class byte that should be used with cards of this profile
                 sel_ctrl : selection control bytes class byte that should be used with cards of this profile
+                addons: List of optional CardAddons that a card of this profile might have
         """
         self.name = name
         self.desc = kw.get("desc", None)
@@ -97,6 +98,8 @@ class CardProfile:
         self.shell_cmdsets = kw.get("shell_cmdsets", [])
         self.cla = kw.get("cla", "00")
         self.sel_ctrl = kw.get("sel_ctrl", "0004")
+        # list of optional addons that a card of this profile might have
+        self.addons = kw.get("addons", [])
 
     def __str__(self):
         return self.name
@@ -161,3 +164,34 @@ class CardProfile:
                 return p()
 
         return None
+
+    def add_addon(self, addon: 'CardProfileAddon'):
+        assert(addon not in self.addons)
+        # we don't install any additional files, as that is happening in the RuntimeState.
+        self.addons.append(addon)
+
+class CardProfileAddon(abc.ABC):
+    """A Card Profile Add-on is something that is not a card application or a full stand-alone
+    card profile, but an add-on to an existing profile.  Think of GSM-R specific files existing
+    on what is otherwise a SIM or USIM+SIM card."""
+
+    def __init__(self, name: str, **kw):
+        """
+        Args:
+                desc (str) : Description
+                files_in_mf : List of CardEF instances present in MF
+                shell_cmdsets : List of cmd2 shell command sets of profile-specific commands
+        """
+        self.name = name
+        self.desc = kw.get("desc", None)
+        self.files_in_mf = kw.get("files_in_mf", [])
+        self.shell_cmdsets = kw.get("shell_cmdsets", [])
+        pass
+
+    def __str__(self):
+        return self.name
+
+    @abc.abstractmethod
+    def probe(self, card: 'CardBase') -> bool:
+        """Probe a given card to determine whether or not this add-on is present/supported."""
+        pass
diff --git a/pySim/ts_102_221.py b/pySim/ts_102_221.py
index b6c003b8..df8b8421 100644
--- a/pySim/ts_102_221.py
+++ b/pySim/ts_102_221.py
@@ -31,7 +31,9 @@ import pySim.iso7816_4 as iso7816_4
 
 # A UICC will usually also support 2G functionality. If this is the case, we
 # need to add DF_GSM and DF_TELECOM along with the UICC related files
-from pySim.ts_51_011 import DF_GSM, DF_TELECOM
+from pySim.ts_51_011 import DF_GSM, DF_TELECOM, AddonSIM
+from pySim.gsm_r import AddonGSMR
+from pySim.cdma_ruim import AddonRUIM
 
 ts_102_22x_cmdset = CardCommandSet('TS 102 22x', [
     # TS 102 221 Section 10.1.2 Table 10.5 "Coding of Instruction Byte"
@@ -768,6 +770,11 @@ class CardProfileUICC(CardProfile):
             # FIXME: DF.CD
             EF_UMPC(),
         ]
+        addons = [
+            AddonSIM,
+            AddonGSMR,
+            AddonRUIM,
+        ]
         sw = {
             'Normal': {
                 '9000': 'Normal ending of the command',
@@ -839,7 +846,7 @@ class CardProfileUICC(CardProfile):
 
         super().__init__(name, desc='ETSI TS 102 221', cla="00",
                          sel_ctrl="0004", files_in_mf=files, sw=sw,
-                         shell_cmdsets = [self.AddlShellCommands()])
+                         shell_cmdsets = [self.AddlShellCommands()], addons = addons)
 
     @staticmethod
     def decode_select_response(resp_hex: str) -> object:
@@ -895,4 +902,5 @@ class CardProfileUICCSIM(CardProfileUICC):
 
     @staticmethod
     def match_with_card(scc: SimCardCommands) -> bool:
-        return match_uicc(scc) and match_sim(scc)
+        # don't ever select this profile, we only use this from pySim-trace
+        return False
diff --git a/pySim/ts_51_011.py b/pySim/ts_51_011.py
index 1f98e724..c81bfdfb 100644
--- a/pySim/ts_51_011.py
+++ b/pySim/ts_51_011.py
@@ -30,9 +30,10 @@ order to describe the files specified in the relevant ETSI + 3GPP specifications
 #
 
 from pySim.profile import match_sim
-from pySim.profile import CardProfile
+from pySim.profile import CardProfile, CardProfileAddon
 from pySim.filesystem import *
 from pySim.ts_31_102_telecom import DF_PHONEBOOK, DF_MULTIMEDIA, DF_MCS, DF_V2X
+from pySim.gsm_r import AddonGSMR
 import enum
 from pySim.construct import *
 from construct import Optional as COptional
@@ -1047,8 +1048,12 @@ class CardProfileSIM(CardProfile):
             },
         }
 
+        addons = [
+            AddonGSMR,
+        ]
+
         super().__init__('SIM', desc='GSM SIM Card', cla="a0",
-                         sel_ctrl="0000", files_in_mf=[DF_TELECOM(), DF_GSM()], sw=sw)
+                         sel_ctrl="0000", files_in_mf=[DF_TELECOM(), DF_GSM()], sw=sw, addons = addons)
 
     @staticmethod
     def decode_select_response(resp_hex: str) -> object:
@@ -1104,3 +1109,17 @@ class CardProfileSIM(CardProfile):
     @staticmethod
     def match_with_card(scc: SimCardCommands) -> bool:
         return match_sim(scc)
+
+
+class AddonSIM(CardProfileAddon):
+    """An add-on that can be found on a UICC in order to support classic GSM SIM."""
+    def __init__(self):
+        files = [
+            DF_GSM(),
+            DF_TELECOM(),
+        ]
+        super().__init__('SIM', desc='GSM SIM', files_in_mf=files)
+
+    def probe(self, card:'CardBase') -> bool:
+        # we assume the add-on to be present in case DF.GSM is found on the card
+        return card.file_exists(self.files_in_mf[0].fid)