I have a client that had a Vodavi system. A we installed a Avaya IPO500. This client likes to have his phone speaker volume loud, and with that is my problem. At top volume of the 9508 series phone the call is distorted, where with the old Vodavi system phones were louder when using the speaker. I have place the phones side by side with both systems working and heard the difference. I have looked at new NEC and Panasonic systems and noticed same issue. Is there a new system out there that has a loud desk phone speaker that won't distort the call?

Which NEC system? The 9100 and 8100 speakerphones are fantastic. Almost all older EKT phone IMHO had better sound quality.

If the Vodavi was an analog system, you will not find an IP phone that can match the audio quality. Analog sound gives you everything. IP and all the systems using the sample rate can't produce a high enough sample rate to compare to analog. Some systems have higher sample rates and they get close, but nothing reaches analog quality.

Rcaman

Rcaman is correct.

Your talking yesterdays technology,compared to today's.

IP Phones (9508), has HD voice quality. Not great for speaker phone.

HD Voice quality is usually much better then the old analog.(don't know why, but it is).

Thank you all... Please continue writing. I will need all this so I can show my boss who only knows what a computer does and no idea about phones. But I'm using digital phones not VoIP phones and used analog lines to both the system.
Does the ESI system have loud desktop speaker phones?

If you need a speakerphone for a large room don't screw around and just get an analog Polycom conference phone.