Below is a chart detailing valid phone configurations and use of SIP credentials for Hosted PBX 1.0. BLF, Call Pickup, and Speed Dial are NOT included in the image details. The main purpose of the image is to show that you cannot reuse SIP Credentials on any devices, even when SIP Credentials are interchanged between users.
The flow chart below details the use of SIP credentials for Users and devices on the same Hosted PBX server and account. HOWEVER, SIP credentials from different Hosted PBX servers and accounts CAN be used.
User 1's SIP credentials from hpbx012.serverdata.net can be configured as line button 1 on a Cisco SPA303 AND User 2's SIP credentials from hpbx015.serverdata.net can be configured as line button 2 on the SAME Cisco SPA303, provided that BOTH of the SIP credentials are not used anywhere else and are unique.