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
- Your mobile carrier must offer it on the specific device plan
- Your device and Operating System must support it, which is obvious when the option is available in your Settings
- 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) - 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:
epdg.epc.mnc720.mcc302.pub.3gppnetwork.org|ud4500
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.