Bought a new (to me, but used) Nokia 7510 on eBay, inserted my SIM and fBired it up. When I try to acess the menu. I get the message "Network Busy". I can make calls by dialing them but can not get into my contact list from the SIM. Is this a known problem or did the seller sell me a bad phone? Also the included battery is a BL-4B, but the manual says it shouild be a BL-5BT. Both are 3.7V batteries and the phone does power up without issues, but could this be part of my problem?