SPA525G2 Not Pairing To Bluetooth

[NateT]

I have an SPA525G2 desk phone that will not pair to certain headsets. Sometimes they do not even show up in the scan list. I updated the firmware to 7.6.2f using the Bluetooth firmware version but it did not help. Hardware version is 2.1.1

The headset I am trying to pair (Soundcore Life U2i) is not technically a call center style headset but does show up in the list. I know when pairing I have to enter a pin (0000) and if I leave it blank it demands a pin. I have restarted the phone many times and gone through the scan & pair process many times as well.

Is this a Bluetooth version compatibility related problem? I know the phone is up there in age and this headset is only about a year old.

I tried looking for a workaround using the headphone jack and a Bluetooth adapter but they are meant for use with something like a car stereo aux input because they use 3 pole jacks and not the 4 pole with the mic channel.

Any suggestions? Using a softphone is not an available option in my scenario.

[pieterh]

1) your Soundcore Life U2i apear to be Bluetooth version V5.0 compatible ( A3213 Soundcore Life U2i User Manual.pdf)
according to Different Bluetooth Versions: What You Need to Know | Headphonesty ,  Bluetooth 5, was released in July 2016
the datasheet for the phone Cisco SPA525G2 5-Line IP Phone - Cisco is  last updated in 2010,
so this phone is released before that year
it is safe to assume they run different bluetooth versions, 

2) it is possible the phone has a limited list to present discovered bluetooth devices
if there are more devices than the list allows, your headphone may not appear
=> try in an environment with less bluetooth devices present or refresh the list frequently
NB! bluetooth 5 is low-energy, this may also contribute to unpredictable discovery by the phone

3) according to this: Enable Bluetooth on SPA525G/SPA525G2 IP Phone - Cisco
 The SPA525G/SPA525G2 can be used as a Bluetooth Hands free for the cell phone
=> it may not be able to use the phone connected to both mobile phone and headset at the same time

[NateT]

1.) Thanks for cross referencing the specs! I am not sure where the functionality drops off between the BT versions - that being the U2i shows up in the list but won't pair. If it was incompatible would it even show up in the list?

2.) I think your onto something as the list is always really long but I never payed attention to the exact number the list tops out at. That would explain why sometimes the device I am scanning for does not show up and other times it does. Problem is even when I can find the device I am trying to pair in the scan list (U2i) it fails to pair no matter how many times I scan and attempt pairing.

3.) I am not sure what you mean by this, sounds like your implying I can pair my mobile phone to the SPA525 and use that to answer calls? Then possibly whatever BT headset that is paired to the mobile phone will pass-through to my SPA525?