1. Go to Account-Basic to configure.

Outbound proxy serverOutbound Proxy Server is used to receive all initiating request messages and route them to the designated SIP server.

 For example:

Outbound proxy server

Transport TypeTransport Type: To display and configure transport type for SIP message.
UDP: UDP is an unreliable but very efficient transport layer protocol.
TCP: Reliable but less-efficient transport layer protocol.
TLS: Secured and Reliable transport layer protocol.
DNS-SRV: DNS record for specifying the location of services.

NATNAT: To display and configure NAT settings.
STUN: Short for session traversal utilities for NAT, a solution to solve NAT issues.

2. Go to Account-Advanced to configure.

UDP Keep Alive message: If enabled, the phone will send UDP keep-alive message periodically to router to keep NAT port alive.
UDP Alive Msg Interval: Keep alive message interval.
Rport: Remote port, if enabled, it will add remote port into outgoing SIP message for designated account. 

User agent
One can customize user agent field in the SIP message. If user agent is set to specific value, users can see the information from PCAP. If user agent is not set by default, users can see the company name, model number and firmware version from PCAP.