diff --git a/README.md b/README.md
index 05230f3..4d1b24b 100644
--- a/README.md
+++ b/README.md
@@ -14,9 +14,16 @@ https://github.com/WillCodeForCats/rcell-smsclient
 * chmod 755 /usr/local/bin/asteriskcontactid.pl
 
 ## Configuration
+Configure the following settings for Asterisk.
+
 asterisk.conf:
 * mindtmfduration = 40
 
 alarmreceiver.conf:
 * eventcmd = /usr/local/bin/asteriskcontactid.pl
 * eventspooldir = /var/spool/asterisk/alarmreceiver
+
+## Recommended FXS Adapter
+The Grandstream HT802 configured for DTMF inband and passthrough is recommended for connecting a Contact ID dialer to Asterisk.
+
+* https://www.grandstream.com/products/gateways-and-atas/analog-telephone-adaptors/product/ht802