Problem:
The X-Lite SIP Softphone software application (developed by CounterPath) is very slow to register on the network and dialed calls take 60-120 seconds to connect.

Figure 1: X-Lite Softphone

Note: The X-Lite application is also distributed under various OEM brands by VoIP service providers and others.


Resolution:
Some versions of X-Lite exhibit this behavior if the PC is sending DNS requests to a DNS-Relay agent rather than directly to a DNS Server for resolution.  By default, DHCP configurations assigned by the LAN-Cell will set the LAN-Cell's LAN IP address as the DNS server for the client PC and the LAN-Cell will process the DNS requests as necessary.

You can force the LAN-Cell to assign specific DNS Server addresses during the DHCP process.  Go to ADVANCED -> DNS -> DHCP (see Figure 2).  For the LAN, WLAN, or DMZ subnet where your PC is located, change the DNS Server values to FROM ISP and CELLULAR 1st DNS, etc.  (Select WAN ISP if you are using the wired Ethernet WAN port for primary Internet service.)  

Then release and renew the IP address information on your PC to obtain the correct DNS server values.  Optionally, you can statically assign DNS server IP addresses to the IP stack of your PC.

Figure 2: LAN-Cell 2 DNS Server Settings for DHCP Servers

In X-Lite, confirm the following settings:

User Name = User Name for your VoIP account
Password = Password for your VoIP account
Domain = FQDN of your VoIP SIP server
Send Outbound = Domain
IP Address = Discover Global IP
STUN Server = Discover Server
Enable ICE = Yes

Figure 3: X-Lite Account Settings

Figure 4: X-Lite Topology Settings