Sorry for taking so long to reply...but its a busy time for me right now.
Anyways, I checked Asterisk.log when I called my line from my cellphone and this here is all I could find so far:
05 12/16/12 10:41:22.883 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/204@trusted-43d3;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:22.924 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/200@trusted-feff;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:22.965 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/201@trusted-1046;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:23.021 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/206@trusted-0b67;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:23.062 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/203@trusted-58ba;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:23.103 [33;1mNotifyRing from channel SIP/620-0000000d, callerid <unknown> to channel Local/202@trusted-e373;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:25.097 [33;1mNotifyHangup channel Local/202@trusted-e373;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.107 [33;1mNotifyHangup channel Local/203@trusted-58ba;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.118 [33;1mNotifyHangup channel Local/206@trusted-0b67;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.128 [33;1mNotifyHangup channel Local/201@trusted-1046;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.139 [33;1mNotifyHangup channel Local/200@trusted-feff;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.149 [33;1mNotifyHangup channel Local/204@trusted-43d3;1, reason Unknown[0m <0xb62feb70>
01 12/16/12 10:41:25.159 [31;1mFailed to parse channel SIP/620-0000000d[0m <0xb62feb70>
05 12/16/12 10:41:25.170 [33;1mNotifyHangup channel SIP/620-0000000d, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:25.180 [33;1mNotifyHangup channel Local/204@trusted-43d3;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:25.190 [33;1mNotifyHangup channel Local/202@trusted-e373;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:25.200 [33;1mNotifyHangup channel Local/203@trusted-58ba;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:25.211 [33;1mNotifyHangup channel Local/200@trusted-feff;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:25.221 [33;1mNotifyHangup channel Local/201@trusted-1046;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:25.231 [33;1mNotifyHangup channel Local/206@trusted-0b67;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:41:55.935 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/204@trusted-bcbf;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:55.985 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/200@trusted-61ca;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:56.026 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/201@trusted-2474;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:56.067 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/206@trusted-02ba;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:56.110 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/203@trusted-f083;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:56.152 [33;1mNotifyRing from channel SIP/620-0000000e, callerid <unknown> to channel Local/202@trusted-a540;1, callerid [0m <0xb62feb70>
05 12/16/12 10:41:56.395 [33;1mIgnoring event because exten is 203 is channel is Local/203@trusted-f083;2[0m <0xb62feb70>
01 12/16/12 10:41:56.416 [31;1mFailed to parse channel Local/202@trusted-a540;2[0m <0xb62feb70>
01 12/16/12 10:41:56.426 [31;1mFailed to parse channel Local/200@trusted-61ca;2[0m <0xb62feb70>
01 12/16/12 10:41:56.436 [31;1mFailed to parse channel Local/201@trusted-2474;2[0m <0xb62feb70>
01 12/16/12 10:41:56.446 [31;1mFailed to parse channel Local/206@trusted-02ba;2[0m <0xb62feb70>
05 12/16/12 10:41:56.467 [33;1mIgnoring event because exten is 204 is channel is Local/204@trusted-bcbf;2[0m <0xb62feb70>
05 12/16/12 10:41:56.507 [33;1mNotifyHangup channel Local/202@trusted-a540;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.518 [33;1mNotifyHangup channel Local/201@trusted-2474;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.538 [33;1mNotifyHangup channel Local/206@trusted-02ba;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.548 [33;1mNotifyHangup channel Local/206@trusted-02ba;2, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.559 [33;1mNotifyHangup channel Local/202@trusted-a540;2, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.579 [33;1mNotifyHangup channel Local/200@trusted-61ca;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.590 [33;1mNotifyHangup channel Local/201@trusted-2474;2, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:41:56.600 [33;1mNotifyHangup channel Local/200@trusted-61ca;2, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:42:02.129 [33;1mNotifyHangup channel Local/203@trusted-f083;1, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:42:02.139 [33;1mNotifyHangup channel Local/204@trusted-bcbf;1, reason Unknown[0m <0xb62feb70>
01 12/16/12 10:42:02.150 [31;1mFailed to parse channel SIP/620-0000000e[0m <0xb62feb70>
05 12/16/12 10:42:02.160 [33;1mNotifyHangup channel SIP/203-0000000f, reason Normal Clearing[0m <0xb62feb70>
01 12/16/12 10:42:02.170 [31;1mFailed to parse channel Local/203@trusted-f083;2[0m <0xb62feb70>
05 12/16/12 10:42:02.180 [33;1mNotifyHangup channel SIP/204-00000010, reason Normal Clearing[0m <0xb62feb70>
01 12/16/12 10:42:02.190 [31;1mFailed to parse channel Local/204@trusted-bcbf;2[0m <0xb62feb70>
05 12/16/12 10:42:02.200 [33;1mNotifyHangup channel SIP/620-0000000e, reason Unknown[0m <0xb62feb70>
05 12/16/12 10:42:02.211 [33;1mNotifyHangup channel Local/204@trusted-bcbf;2, reason Normal Clearing[0m <0xb62feb70>
05 12/16/12 10:42:02.221 [33;1mNotifyHangup channel Local/203@trusted-f083;2, reason Normal Clearing[0m <0xb62feb70>
The interesting part is, that I have another sipphone hooked to the fritzbox parallel to LMCE, but there I get callerid shown, so clearly the box is sending them. Unfortunately I was so far unsuccessful in finding out how it is sending them.