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Kallin lets you bring your existing UK phone numbers into one place, so you can manage call routing, voicemail, IVR menus, and more without switching providers or losing the numbers your customers already know. Whether you have a BT landline, a VoIP number, or a mobile number from any of the major UK networks, Kallin connects to it using the method that suits your setup best — no hardware required.

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Connection Methods

BT & Openreach Landlines

Connect geographic 01/02 numbers, ISDN lines, or SIP trunks provisioned through BT or Openreach to Kallin for full call management.

VoIP Providers

Link numbers from UK VoIP providers such as Vonage, 8x8, RingCentral, Gamma, and others via SIP trunking or call forwarding.

Mobile Networks

Connect your Vodafone, O2, EE, or Three UK mobile number using call divert — no SIM card swap or extra hardware needed.

Number Porting

Permanently transfer your existing UK phone number from any Ofcom-regulated provider directly to Kallin.

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What You’ll Need

Before you start, make sure you have the following to hand:
  • Your phone number in full, including the area code (e.g. 01234 567890 or 07700 900123)
  • Access to your provider account — you’ll need to be the account holder or an authorised contact to verify ownership or make changes such as setting up call divert
  • Proof of ownership — required if you are porting your number; this typically means your account number and, for mobile numbers, a Port Authorisation Code (PAC)

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Connection Process Overview

Regardless of which provider type you are connecting, the overall process follows the same four steps:
1

Choose Your Provider Type

Identify whether your number is hosted by a BT/Openreach landline, a VoIP provider, or a mobile network — or decide whether you want to port it permanently to Kallin.
2

Follow the Provider-Specific Guide

Use the relevant guide in this section to walk through the exact steps for your provider, including any configuration you need to make on the provider side.
3

Verify the Number

Kallin will confirm that you own or control the number, either by sending a verification call, an SMS, or by checking the details you provide during porting.
4

Configure Routing

Once your number is connected and verified, set up your call routing rules, IVR menus, voicemail, and any other settings in the Kallin dashboard.
Kallin supports all UK Ofcom-regulated number ranges, including geographic numbers (01/02), non-geographic numbers (03), freephone numbers (0800/0808), and mobile numbers (07). Premium-rate numbers (09) are not supported.
If you want to move your number away from your current provider entirely and manage everything through Kallin, see the Number Porting guide. Porting gives you full control without relying on your old provider’s forwarding configuration.