How to manually configure Cisco IP phones

1. Login to the phone

2. Goto the Ext1 top left tab

3. Proxy and Registration section put your servers domain.tld in the proxy field

4. Subscriber Information section put the extension number for Display Name and User ID

5. Password put the extensions password

6. Click Submit All Changes at the bottom

Once you have that done, make sure the p-time is set to 0.020

1. Click the advanced option at the top right

2. Goto the SIP tab at the top

3. Scroll down to the RTP Parameters section and make sure the RTP Packet Size field has 0.020

4. Click Submit All Changes at the bottom