EE Wi-Fi Calling does not initiate on specific networks (no DNS / no IPSec)

[Thomaschui]

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Hi EE,

I’m trying to understand a Wi-Fi Calling behaviour specific to EE, which appears to be location / public-IP dependent, rather than a handset or Wi-Fi issue.

Summary

On certain Wi-Fi networks, EE Wi-Fi Calling does not initiate at all:

• No DNS queries

• No UDP 500 (IKE)

• No UDP 4500 (IPSec NAT-T)

This has been verified with packet capture (Wireshark) on both iOS and Android.

The same Wi-Fi network successfully supports Wi-Fi Calling for O2, Vodafone and Three.

Test results

Locations

• ✅ Reading – EE Wi-Fi Calling works normally

• ❌ Newbury – EE Wi-Fi Calling never initiates

• ❌ Bristol – same behaviour as Newbury

Behaviour in Newbury / Bristol

• Airplane mode + Wi-Fi: waited 60+ seconds, no Wi-Fi Calling

• Attempting to place a call: no Wi-Fi Calling

• Packet capture shows:

  • No DNS queries

  • No IPSec attempt

• IPv4 only

• DNS tested:

  • BT DNS

  • Google (8.8.8.8)

  • Cloudflare (1.1.1.1)
    → No difference

• No captive portal

Controls

• Same Wi-Fi, same devices:

  • O2 / Vodafone / Three can all establish Wi-Fi Calling

  • Works both in airplane mode and normal mode

• EE SIM works fine:

  • At home

  • In Reading

• Reading and Newbury have identical local network configuration, only the public IP differs

Devices

• EE consumer SIM

• iOS 26.1

• Android (same result)

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Conclusion

This does not appear to be:

• a Wi-Fi issue

• a DNS issue

• a handset or OS issue

It looks like EE Wi-Fi Calling is being prevented from initiating by an internal pre-check / policy decision, likely based on public IP / routing / location, as the client does not even start the DNS or IPSec phase.

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Question

Can this be reviewed or escalated to the EE network / IMS / Wi-Fi Calling team to confirm whether this behaviour is expected or configurable?

I’m happy to provide further technical details if needed.

Thanks.

[XRaySpeX]

Who is the BB provider in the 3 locations? Using which router?

[Thomaschui]

All locations are using BT 500 Mbps leased lines, and the router in use is a TP-Link ER8411.

The key point is that the same router model, firmware and configuration is used in Reading and Newbury.

• Reading: EE Wi-Fi Calling works normally
• Newbury / Bristol: EE Wi-Fi Calling does not initiate at all

The only difference between these sites is the public IP / routing provided by the BT leased line, not the local router, firewall or Wi-Fi configuration.

On the same ER8411 router and Wi-Fi network, Wi-Fi Calling works immediately with O2, Vodafone and Three SIMs, both in and out of airplane mode.

Packet capture confirms that in Newbury/Bristol the EE Wi-Fi Calling client does not even begin DNS resolution or IPSec negotiation, which suggests a decision made before Wi-Fi Calling setup, rather than traffic being blocked by the router or ISP.

If EE Wi-Fi Calling has any specific requirements or exclusions related to leased-line IP ranges, routing, MTU, or NAT behaviour, I’m happy to validate those – but based on the identical setup comparison, this appears to be EE-specific behaviour.