ADRNR details

Hi,

I need to download/modify the vendor & customer details like Phone No ,Fax No and EMail Address. Are there any BAPI's by which I can do this. Say I can get ADRNR number for a given vendor(LFA1) or customer(KNA1)..by using this ADRNR...are there any FM/BAPI I can download or modify the above details??? Request you to please post only useful details.