WiFi calling with adam:GO™

Background to WiFi calling

Mobile carriers typically offer phone services via cellular towers. Sometimes the coverage is suboptimal and an alternative way of getting a voice connection is essential. If you happen to have a higher quality WiFi signal than Cellular signal, WiFi calling may be an option.

Requirements for WiFi calling

  1. Your mobile carrier must offer it on the specific device plan
  2. Your device and Operating System must support it, which is obvious when the option is available in your Settings
  3. Your network must allow outbound UDP port 500 and UDP port 4500 (IPSec NAT Traversal) to *.3gppnetwork.org (in the case of adam:ONE® that is managed, this domain is already part of your default policies)
  4. When activating, a one-time 911 registration must take place on your mobile device, unencumbered by any other concurrent VPN running during registration (if running adam:GO™ at the time, temporarily drop the always-on VPN during registration)

How WiFi calling works

When you enable WiFi calling on a modern smartphone, it makes an IKEv2 IPSec VPN connection to an orchestration service provided by 3GPP. We’ve never seen a mobile carrier use anything else. These are common hosts used by various mobile carriers:

FQDN of VPN hosts we regularly observe Carrier
config.rcs.mnc001.mcc655.pub.3gppnetwork.org Vodacom South Africa
config.rcs.mnc610.mcc302.pub.3gppnetwork.org Bell Canada
epdg.epc.mnc000.mcc000.pub.3gppnetwork.org Kerna Communications Ireland
epdg.epc.mnc001.mcc238.pub.3gppnetwork.org TDC NET Denmark
epdg.epc.mnc001.mcc286.pub.3gppnetwork.org Turkcell’le Turkey
epdg.epc.mnc001.mcc505.pub.3gppnetwork.org Telstra Australia
epdg.epc.mnc001.mcc620.pub.3gppnetwork.org Vodafone Ghana
epdg.epc.mnc001.mcc655.pub.3gppnetwork.org Vodacom South Africa
epdg.epc.mnc001.mcc740.pub.3gppnetwork.org Claro Ecuador
epdg.epc.mnc002.mcc286.pub.3gppnetwork.org Vodafone Turkey
epdg.epc.mnc002.mcc404.pub.3gppnetwork.org Airtel India
epdg.epc.mnc002.mcc655.pub.3gppnetwork.org Telkom South Africa
epdg.epc.mnc003.mcc214.pub.3gppnetwork.org Orange Spain
epdg.epc.mnc003.mcc286.pub.3gppnetwork.org AVEA Turkey
epdg.epc.mnc003.mcc515.pub.3gppnetwork.org Smart Phillipines
epdg.epc.mnc004.mcc214.pub.3gppnetwork.org Kerna Communications Ireland
epdg.epc.mnc006.mcc268.pub.3gppnetwork.org Telepac Portugal
epdg.epc.mnc007.mcc214.pub.3gppnetwork.org Telefonica Spain
epdg.epc.mnc007.mcc655.pub.3gppnetwork.org MTN South Africa
epdg.epc.mnc008.mcc240.pub.3gppnetwork.org Telenor Sweden
epdg.epc.mnc010.mcc234.pub.3gppnetwork.org O2 Europe
epdg.epc.mnc010.mcc655.pub.3gppnetwork.org MTN Business South Africa
epdg.epc.mnc010.mcc724.pub.3gppnetwork.org TData Brazil
epdg.epc.mnc015.mcc234.pub.3gppnetwork.org Vodafone UK
epdg.epc.mnc020.mcc334.pub.3gppnetwork.org Deprecated
epdg.epc.mnc023.mcc724.pub.3gppnetwork.org TData Brazil
epdg.epc.mnc030.mcc234.pub.3gppnetwork.org EE UK
epdg.epc.mnc030.mcc334.pub.3gppnetwork.org Kerna Communications Ireland
epdg.epc.mnc040.mcc404.pub.3gppnetwork.org Airtel India
epdg.epc.mnc045.mcc404.pub.3gppnetwork.org Airtel India
epdg.epc.mnc076.mcc404.pub.3gppnetwork.org Kerna Communications Ireland
epdg.epc.mnc084.mcc404.pub.3gppnetwork.org Deprecated
epdg.epc.mnc086.mcc404.pub.3gppnetwork.org Deprecated
epdg.epc.mnc220.mcc302.pub.3gppnetwork.org Telus Canada
epdg.epc.mnc240.mcc310.pub.3gppnetwork.org T-Mobile USA
epdg.epc.mnc260.mcc310.pub.3gppnetwork.org T-Mobile USA
epdg.epc.mnc370.mcc302.pub.3gppnetwork.org Rogers Canada
epdg.epc.mnc490.mcc302.pub.3gppnetwork.org Globalive Canada
epdg.epc.mnc580.mcc311.pub.3gppnetwork.org Service Provider Corporation USA
epdg.epc.mnc610.mcc302.pub.3gppnetwork.org Bell Canada
epdg.epc.mnc720.mcc302.pub.3gppnetwork.org Rogers Canada
epdg.epc.mnc780.mcc302.pub.3gppnetwork.org Sasktel Canada
epdg.epc.mnc861.mcc405.pub.3gppnetwork.org Reliance Jio Infocomm India
epdg.epc.mnc874.mcc405.pub.3gppnetwork.org Reliance Jio Infocomm India
epdg.epc.mnc880.mcc302.pub.3gppnetwork.org Kerna Communications Ireland
epdg.ims.mnc005.mcc724.pub.3gppnetwork.org Claro Brazil
epdg.ims.mnc020.mcc334.pub.3gppnetwork.org RadioMovil Mexico
epdg.ims.mnc101.mcc732.pub.3gppnetwork.org Comcel Columbia
h-slp.mnc001.mcc655.pub.3gppnetwork.org Deprecated
ss.epdg.epc.mnc260.mcc310.pub.3gppnetwork.org T-Mobile USA

Additional considerations for a better experience

Smartphone IPSec connections often attempt to stay connected to a destination IP beyond its Time to Live (TTL), in which case this Enabler instructs the gateway to keep UDP port 4500 open indefinitely:


The above line is an example; it can be repeated for any carrier networks you use, or the entire list. The list above includes top 50 carriers we have observed. To find out why ones you may be using, mytools.management/log reports your usage in real-time.

Additional details

WiFi calling IPSec tunnel is a Split VPN tunnel and only WiFi calling traffic routes over this network. Any other IPSec connection runs concurrently, even if the other network is a Full VPN tunnel, i.e. it routes all remaining traffic by default. To illustrate this, your mobile device that is adam:GO™ enabled with an always-on VPN, will have the following two concurrent connections:

VPN purpose Destination Type
WiFi Calling host-abc.3gppnetwork.org Split-VPN (Voice traffic only)
Always-on VPN for Zero Trust client-abc.adamuser.app Full VPN (all other traffic)

Note about managed clients

The support and provisioning outlined above is automatically included for adam:GO deployments.