Hi Ladysolitary85
I just saw your audiogram in your "Allegeries? Fluid in Your Ear?" thread.
You might want to try using a portable telephone amplifier. There are two kinds.
If the business phone is not a cordless phone but a regular landline and has a separate handset from the base of the phone - you can try an in-line amplifier.
Set up is usually like this:
Hookup ampliier box to the telephone base where the curly cord of the phone usually hooks up to , hook up one end of the curly cord to the amplifier box and the other end end to the handset.
Example:
Amazon.com: Ameriphone HA40 In-Line Telephone Handset Amplifier: Electronics
This type of amplifier can help, but it won't make the telephone hearing aid compatible if its not already.
You can also try a portable handset that attaches to the ear piece of the phone's handset.
This might be a better way to go because not all telephones are equally hearing aid compatible (even including landlines with built in volume control), but the second kind of portable telphone amplifier, because of its design and how its used, can help make the phone more hearing aid compatible.
Example:
Amazon.com: Serene Portable Phone Amplifier 30dB: Health & Personal Care
It depends on your word discrimination scores how much help this approach will be. If your word discrimintion scores are good or even fair, it will probably help. If it isn't -- you will still just get noise, just louder noise.
AFAICT, your audiogram didn't include word discrimination scores.
FWIW, I've used Ameriphone but haven't used Serene, and I've used both kinds of portable telephone amplifiers. I just linked to the brands that Amazon happened to be selling today.
Both type of amplifiers use batteries. People that hear well will probably be able to hear the other side of the phone call if they are nearby.
Hope this helps.