I could talk your head off about Alice-DSL, and if you push me, I just might. But what I wanted to post here, for posterity, are instructions to get your Siemens SL2-141-I ADSL modem up and functioning correctly, including WLAN. I also toiled with a Siemens C2-010-I but gave up since I had another basic wired router on hand that was easier to set up.
But whatever Alice-provided modem you have, there may be some generally useful information here, though I do assume a certain level of computer/modem knowledge which probably makes this not the best guide for the technophobe. For orientation purposes, I'm a US-American with a lot of computer experience and a top-of-the-line US laptop (IBM/Lenovo) running Windows XP. I've never had trouble in the past connecting to various WLAN or cabled modems in the US and abroad. I assumed the same would be the case this time: Alice-DSL service in Berlin with a Siemens SL2-141-I ADSL WLAN/wireless modem. But alas, no.
(You CAN SKIP this part if you just want the solution - but this may help you orient yourself and I need to get it off my chest 'cause Alice really pisses me off sometimes.) Well, the "software" they send doesn't setup on my system. I call it "software" (in quotes) because it's really just a glorified setup assistent which, in any case, fails at its job. In fact the CD is loaded with other outdated software, like IE6 (at the time of this writing IE7 is installed to new machines and those with Windows Update turned on). I'm not sure when Alice would have you install this junk, probably without asking or checking whether you wanted it. But just so you know where I'm coming from - many of you've probably had these problems - the first error I get regards the language of my operating system not being supported. Fine, change that in the Start->Control Panel->Regional and Language Settings, restart and you get further. Next error - which BTW you can't see on my system because it's hidden behind an install window that can't be minimized but you can run the install in smaller steps manually (not worth explaining here but check out the files on the CD if you're curious) - relates to the Alice "software" not being able to recognize my hardware (i.e., Intel Wireless and Ethernet adapters). Instead of detecting my components and setting up a connection profile, it tried to setup my built-in modem card to run direct off the DSL line, a fine solution if (1) I didn't want a wireless connection and (2) they hadn't sent me an external modem/router (by which I could and do connect several computers). Almost needless to say, when the Alice "Einrichtungsassistent" then runs, it can't find an internet connection - I did NOT plug the DSL line into my built-in modem - and if I chose the SL2-141-I from a list, it refused to see it.
Now I'm not entirely sure why I even bothered with the Alice "software" since I'm typically the kind of guy who avoids such company-distributed materials - I even format the hard drive on a brand new computer to remove all traces of hardware-branded software and reinstall the OS from scratch. But it was a simple task, so I thought I'd give Alice a chance. I thought that perhaps the average German could program better software. Wrong. So I set the SL2-141-I up the "easy" way: manually. Problem is, there are a few hitches here too, thanks to Alice.
(Read here for the SOLUTION.) Out of the box the SL2-141-I WLAN signal was turned on; took me a moment to notice they'd printed the WEP key/schlussel on a sticker on the bottom of router (completely idiotic given that it's user-configurable but whatever). So things started out well, but then the problems began. It (1) wouldn't hand me an IP-Address dynamically (i.e., via DHCP), which I confirmed at the command line (Run->cmd) with "ipconfig" (try it rather than reading the stupid Windows wireless pop-up boxes that try to inform you about the failed state of the connection). What to do here requires a bit of background knowledge. Most routers, including the SL2-141-I, are given the default gateway IP address of 192.168.1.1 (sometimes you see 0.1 or 2.1) and have built-in management tools that you can access via a web browser. So I setup the connection with a static IP address (e.g., 192.168.1.2 subnet 255.255.255.0), and tried to access the modem's configuration manager via HTTP (i.e.,
http://192.168.1.1/ in a web browser). Only (2) it needed a username and password that wasn't given in any of the Alice documentation. After a bit of cursing and a quick
Google search, I found the following username:password pair (alice@13184:hnto$mgmt@lice) posted by a nice guy out in the ether (http://www.hansenet-user-forum.de/viewtopic.php?p=86713&sid=043b02d8b328acee31d4499c7ea28cf9). Another person had suggested ADMIN:ADMIN, but that didn't work for me, the former did. Where Alice came up with this pair baffles me. Once into the SL2-141-I management tools, I could plainly see that Alice had turned off DHCP. Why the f*&k would they do that?! So I turned it back on and reestablished my IP dynamically. Then I needed to set up the internet connection. Big surprise, (3) the Quick Connect tool didn't get the parameters right because Alice has everything configured in a complicated way to carefully dole out their bandwidth and services. So I noted that the SL2-141-I can backup and restore configurations to/from an XML file (another typical router property), and used an archive tool (WinRAR) to search the archives and executables on the Alice CD for XML files. Two come up, the first one (Profile1.xml), which unfortunately I can't attach here (I paste it as text below), get's you going. All you need then is your Alice username - your festnetz number with vorwahl - and password (on your original contract). I suggest also changing various setting with the SL2-141-I management tool, such as the master username:password, and various security settings such as is appropriate to your setup.
I hope this has helped! Please let me know if you find any mistakes or get stuck somewhere in these directions. Sorry if my (yes native) English has been tainted from having spoken too much crass German

. Tschüss!
---- Profile1.xml ----
<psitree>
<ADSL>
<settings G.Dmt="enable" G.lite="enable" T1.413="enable" ADSL2="enable" AnnexL="enable" ADSL2plus="enable" AnnexM="disable" pair="inner" bitswap="enable" SRA="disable" ADSLenable="enable"/>
</ADSL>
<AtmCfgTd>
<td1 cat="UBR" PCR="0" SCR="0" MBS="0"/>
</AtmCfgTd>
<AtmCfgVcc>
<vccId1 vpi="2" vci="32" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
<vccId2 vpi="2" vci="33" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
<vccId3 vpi="1" vci="34" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
<vccId4 vpi="1" vci="32" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
<vccId5 vpi="8" vci="35" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
<vccId6 vpi="0" vci="35" tdId="1" aalType="AAL5" adminStatus="up" encap="llc" qos="disable"/>
</AtmCfgVcc>
<wan_2_32>
<entry1 vccId="1" conId="1" name="br_2_32" protocol="BRIDGE" encap="LLC" firewall="disable" nat="disable" igmp="disable" vlanId="-1" service="enable" remoteWeb="0" remoteTelnet="0" remoteSnmp="0" remotePing="0" remoteFtp="0" remoteTftp="0" remoteSsh="0" remoteipauth="0" remoteWebPort="8080" traffictype="0" vlangroup="STB"/>
</wan_2_32>
<SystemInfo>
<sysLog state="enable" displayLevel="ERR" logLevel="DEBUG" option="local" serverIP="0.0.0.0" serverPort="514"/>
<snmp state="disable" readCommunity="public" writeCommunity="private" sysName="Siemens" sysLocation="CH" sysContact="www.siemens.com" trapIP="0.0.0.0" trapStatus="disable"/>
<defaultGateway enblGwAutoAssign="disable" ifName="ipa_0_35" ipAddr="10.100.100.1"/>
<dns dynamic="enable" primary="0.0.0.0" secondary="0.0.0.0"/>
<qosvoice enable="0" ifname="ipa_0_35"/>
<remoteservice value="ipoa_0_35"/>
<authservice value="ipoa_0_35"/>
<protocol autoScan="enable" upnp="disable" igmpSnp ="disable" macFilterPolicy="forward"/>
<ddnsstatus state="disable"/>
<actpppconn value="ipoa_0_35"/>
<domainname value="home"/>
<hostname value="SL2141I"/>
<sysFirewall state="disable"/>
</SystemInfo>
<wan_2_33>
<entry1 vccId="2" conId="1" name="br_2_33" protocol="BRIDGE" encap="LLC" firewall="disable" nat="disable" igmp="disable" vlanId="-1" service="enable" remoteWeb="0" remoteTelnet="0" remoteSnmp="0" remotePing="0" remoteFtp="0" remoteTftp="0" remoteSsh="0" remoteipauth="0" remoteWebPort="8080" traffictype="1" vlangroup="STB"/>
</wan_2_33>
<wan_1_34>
<entry1 vccId="3" conId="1" name="br_1_34" protocol="BRIDGE" encap="LLC" firewall="disable" nat="disable" igmp="disable" vlanId="-1" service="enable" remoteWeb="0" remoteTelnet="0" remoteSnmp="0" remotePing="0" remoteFtp="0" remoteTftp="0" remoteSsh="0" remoteipauth="0" remoteWebPort="8080" traffictype="2" vlangroup="STB"/>
</wan_1_34>
<wan_1_32>
<entry1 vccId="4" conId="1" name="pppoe_1_32_1" protocol="PPPOE" encap="LLC" firewall="enable" nat="enable" igmp="disable" vlanId="-1" service="enable" remoteWeb="0" remoteTelnet="0" remoteSnmp="0" remotePing="0" remoteFtp="0" remoteTftp="0" remoteSsh="0" remoteipauth="0" remoteWebPort="8080" traffictype="3" vlangroup="Default"/>
</wan_1_32>
<wan_8_35>
<entry1 vccId="5" conId="1" name="pppoe_8_35_1" protocol="PPPOE" encap="LLC" firewall="enable" nat="enable" igmp="disable" vlanId="-1" service="enable" remoteWeb="0" remoteTelnet="0" remoteSnmp="0" remotePing="0" remoteFtp="0" remoteTftp="0" remoteSsh="0" remoteipauth="0" remoteWebPort="8080" traffictype="3" vlangroup="Default"/>
</wan_8_35>
<pppsrv_1_32>
<ppp_conId1 userName="{UsernameToSet}" password="{PasswordToSet}" serviceName="" idleTimeout="0" ipExt="disable" auth="auto" demand="0" mtu="1492" useStaticIpAddr="0" localIpAddr="0.0.0.0" pppaddgw="1"/>
</pppsrv_1_32>
<pppsrv_8_35>
<ppp_conId1 userName="{UsernameToSet}" password="{PasswordToSet}" serviceName="" idleTimeout="0" ipExt="disable" auth="auto" demand="0" mtu="1492" useStaticIpAddr="0" localIpAddr="0.0.0.0" pppaddgw="1"/>
</pppsrv_8_35>
<ipsrv_0_35>
<dhcpc_conId1 state="disable" unnumipoa="0" adddfroute="0" wanAddress="10.100.100.2" merdefgw="0" wanMask="255.255.255.0"/>
</ipsrv_0_35>
<wan_0_35>
<entry1 vccId="6" conId="1" name="ipoa_0_35" protocol="IPOA" encap="LLC" firewall="enable" nat="disable" igmp="disable" vlanId="-1" service="enable" remoteWeb="1" remoteTelnet="1" remoteSnmp="1" remotePing="1" remoteFtp="1" remoteTftp="1" remoteSsh="1" remoteipauth="0" remoteWebPort="8080" traffictype="3" vlangroup="Default"/>
</wan_0_35>
<PMapCfg>
<pmapIfcCfg pmapIfName="eth0" pmapIfcStatus="enable"/>
</PMapCfg>
<SecCfg>
<vrtSrv tableSize="0">
</vrtSrv>
<prtTrigger tableSize="0">
</prtTrigger>
<outFilter tableSize="0">
</outFilter>
<inFilter tableSize="0">
</inFilter>
<accessCtrlMode state="disable"/>
<accessCtrl tableSize="0">
</accessCtrl>
<qosCls tableSize="0">
</qosCls>
<dmzHost ipAddr="0.0.0.0"/>
<staticDnsEntry staticDns1="" staticIp1="" staticDns2="" staticIp2="" staticDns3="" staticIp3=""/>
<iptvCfg iptvStatus="0" Interface="eth0.5"/>
<srvCtrlList ftp="enable" http="enable" snmp="enable" ssh="enable" telnet="enable" tftp="enable"/>
</SecCfg>
<DDNSCfg/>
<SNTPCfg/>
<ipauthremote/>
<RouteCfg>
<ripGlobal state="disable" ripIfcTableSize="2"/>
<ripIfc tableSize="4">
<ripIfcEntry id="1" name="br0" state="disable" version="2" operation="active"/>
<ripIfcEntry id="2" name="ipa_0_35" state="disable" version="2" operation="passive"/>
<ripIfcEntry id="3" name="ppp_1_32_1" state="disable" version="1_2" operation="passive"/>
<ripIfcEntry id="4" name="ppp_8_35_1" state="disable" version="1_2" operation="passive"/>
</ripIfc>
<route tableSize="0">
</route>
</RouteCfg>
</psitree>