How do I conference call with model KX-TGDA20?

The KX-TGA641 handset is not compatible with the KX-TGC350 base. The KX-TGC350 communicates with the KX-TGDA20 add-on handset. The included handsets are KX-TGCA35 (1 to 4 handsets depending on the model). See the manual here: https://help.panasonic.ca/viewing/ALL/KX-TGC350/OI/TGC364_PNQX7789XA/TGC364_PNQX7789XA.pdf . You can also check the product page here: https://shop.panasonic.com/cordless-corded-telephones/cordless-telephones/KX-TGC35.html?dwvar_KX-TGC35_handsets=1 .

The KX-TGA641 handset is compatible with the KX-TG6400 series base. See the manual for this expandable cordless telephone system here: https://help.panasonic.ca/viewing/ALL/KX-TG6411/OI/TG6411_PNQX1623YA/TG6411_PNQX1623YA.pdf?a_id=54175&session=tg2XbQ_o . You can also find the handset's manual here: https://shop.panasonic.com/support-only/KX-TGA641T.html . Additional information for the KX-TG64 series phone system is available from one of those product pages: https://shop.panasonic.com/support-only/KX-TG6411T.html .

I wish that I had better news for you. In this case, the base is speaking a different language during registration than the KX-TGA641 is expecting. They will never properly communicate.

Cindy Wells

https://www.manualslib.com/products/Panasonic-Kx-Tgda20-4079532.html

The manual is available from:
http://www.manualslib.com/manual/888692/Panasonic-Kx-Tgd210.html#product-TGDA20

( be sure to ignore the advertising large button
"start download" and use the smaller button "download"
across the top banner "downloads" "table of contents" etc. )
then enter the security-codes & click "Get Manual"
then click 'Download pdf'' etc. )

The directions to record the Answering System Greeting
are on page 30.

To summarize:

1. press [MENU] # 3 0 2
2. scroll up/down to "yes" then press [select]
3. phone will 'beep', begin speaking your greeting message
(up to 2 minutes long) and when you are finished,
4. press [stop] [off]
========================
Good luck!

Operating Instructions (English) - Support - Panasonic

service.us.panasonic.com/.../KXTG4731-MUL.PDF

PanasonicJul 15, 2012 - Voice Mail Service. Voice mail service . .... *1 A range extender (KX-TGA405) is supplied in this model. By installing this unit, .... R This product is unable tomake calls when: ..... minutes, an alarm tone starts to sound and the ringer ...... To see the remaining information .... greeting message, the unit plays a.

[PDF]Operating Instructions (English) - FTP Directory Listing

ftp://ftp.panasonic.com/telephone/om/kxtg6632_mul_om.pdf

Panasonic

The KX-TGA401 is the handset. The greeting is controlled by the answering machine. What model answering machine do you have on your phone line?

you can do as many conferences as you have phones, but one phone can have one conference at a time with 3 total parties(depending on your phone system) in the conference (so yourself and 2 other people, inside or outside of the office)

if you have a TDA/TDE/NCP phone system (blue box on the wall or in a computer rack) you can have 5 people in a single conference...

if you have a TD phone system (white box on the wall) you are limited to a 3 party conference

Axiatel "conference call"solution allow you to plan and organize your conference calls and meeting and you have unlimited minutes,a dedicate number and up to 50 participants :

go have a look,their solutions are online and you can benefit from 30 ay free trial : https://www.axiatel.com/gb/en/conference-call/index.php

You need to put the first party on hold before using the conference button. You can download the manual from the link below: http://www2.panasonic.com/webapp/wcs/stores/servlet/vProdSupportModel?displayTab=R&surfModel=KX-TS3282W&modelNo=KX-TS3282W&storeId=15001&catalogId=11017&itemId=64503&displayServiceCenter=true# Please update the question & let us know if the information given was useful to you - Good Luck!