Cisco 7800 - Inline Amplifier

[stuart.gleaves1]

One of our users requires an inline amplifier due to hearing issue. Cisco recommends either 

Clarity HA-40 Inline Amplifier for Corded Phone or Plantronics EHA40 Inline Amplifier as is EOL.  

Our supplier is unable to source either of them. 

Can anyone recommend an alternative?

Thanks 

[Mike_Brezicky]

I have a couple Walker W-10 amplifiers that are working well on my 7900 series, i assume they would be ok for the 7800's as well.