Reading SIM card isn't supported in master branch of osmocom-bb. To experiment with provider SIM card and network (which is possibly the easiest way to try osmocom-bb out) you will need sylvain/testing branch which you can checkout using following commands:

git clone git://git.osmocom.org/osmocom-bb.git
cd osmocom-bb
git checkout -b testing remotes/origin/sylvain/testing

Next step is to enable CONFIG_TX_ENABLE so we can send data to network

commit af23c7847b275bf957e8aa5b7ee7f48b7ee9a63b
Author: Dobrica Pavlinusic <dpavlin@rot13.org>
Date:   Fri Jan 14 18:44:55 2011 +0100

    enable CONFIG_TX_ENABLE

diff --git a/src/target/firmware/Makefile b/src/target/firmware/Makefile
index 56e0068..c69aab7 100644
--- a/src/target/firmware/Makefile
+++ b/src/target/firmware/Makefile
@@ -73,7 +73,7 @@ ANY_APP_LIBS+=calypso/libcalypso.a layer1/liblayer1.a lib/libmini.a comm/libcomm
 -include Makefile.inc
 
 # Uncomment this line if you want to enable Tx (Transmit) Support.
-#CFLAGS += -DCONFIG_TX_ENABLE
+CFLAGS += -DCONFIG_TX_ENABLE
 
 # Uncomment this line if you want to write to flash.
 #CFLAGS += -DCONFIG_FLASH_WRITE

After that, you should be able to compile working sim reader implementation by running make inside src directory.

Now you can start layer1 and press power button shortly to load it:

cd src/host/osmocon/
./osmocon -p /dev/ttyUSB0 -m c123xor ../../target/firmware/board/compal_e88/layer1.compalram.bin

Now start mobile application:

cd src/host/layer23/src/mobile
./mobile -i 127.0.0.1

this will also start gsmtap which you can use to inspect traffic using Wireshark 1.4 which has gsmtap support:

# sink for gsmtap traffic
nc -u -l 4729 >/dev/null &
sudo wireshark -k -i lo -f 'port 4729'

Depending on your /etc/osmocom/osmocom.cfg you might need to invoke sim reader manually:

$ telnet localhost 4247
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Welcome to the OpenBSC Control interface
OsmocomBB> enable 
OsmocomBB# sim reader 1

after this, you should be able to see sim information using

OsmocomBB# show subscriber 

and place call using

OsmocomBB# call 1 1234567