For the purpose of properly determining the phone's location and providing the correct ELIN, the J100 series phone, when using WiFi, should make the BSSID ID available.
I can think of two ways to make the information available:
  1. Make the info available via SNMP. The ELIN server could query for it after receiving a registration PUBLISH, then use that to provide back the correct ELIN.
  2. The phone should push BSSID via PPM to ASM and ASM should make that info available in the PUBLISH message sent to the ELIN server.
Suggestion 1 seems like it wouldn't be too hard. Suggestion 2 involves both a new firmware on the phone and changes to ASM, so it may take longer.