SAP reduces a lot of phone numbers for the sapserv3 dial in to Walldorf and replaces this with one unique number +49 180 1 SAPNET.
All of you, that are still using the Dial In via ISDN to sapserv3 (other sapservX are not changed at the moment !), should check the ISDN configuration and have to change at least the phone number to +49 1801 727638 (or +49 1801 SAPNET).
If you are using as user "crossX" and not "cross", you have to change the user as well and need to do this at 01.02.2005 or have to open an OSS ticket with SAP earlier.
You can find further information in the SAPNet R/3 Frontend Note 791965.
You should have a look if changing the access to SAP to SNC or VPN via the Internet. This is in most case far cheaper and faster.