Which service providers can sipgate port numbers from?

8x8 UK Limited

Andrews & Arnold

AQL/Telepohny Services

B4RN

Barritel Ltd

Bicom Systems

BT

Buzz Networks

Callagenix Ltd

Causeway Telecom

Central Technology Ltd

Chess LTD

Circle Loop

Cloudcall Ltd

COLT 

Coms.com

Content Guru

Core Telecom

C&W (Cable & Wireless)

Daisy Communications (now Shell)

Dial9

Digital Space

DRD Communications Ltd

DWS

Easynet

Eclipse

Edge Telecom

EE

Entranet

Equiinet/Switch

Essensys Ltd

Eurobell (Holdings) Limited

Excell Group

FleXtel

Fulcrum

Gamma Telecom 

GCI Network Solutions

Global Crossing (UK) Ltd

Gradwell 

Hello Telecom UK

Hive Telecom

Hyperoptic

IDnet

i-Net Communications/Telecoms

iHub

Inclarity plc

Invoco

Invomo

IP Wholesale LTD

John Lewis

Kalnet4U (Tamar)

KCOM (Affiniti)

Kinex

Level 3

Liquid 11

Localphone

Magrathea Telecommunications 

MDNX Enterprise Services Ltd

Metronet UK

Microtalk

Mintaka

Net Solutions Europe 

Net-Work Internet

Network Services Ltd

Nexbridge

NFON UK

Node4 

Nodemax

NowTV

NSN

Numbergroup Network

Numbers Plus

One Bill

Orange 

Orbital

OrbTalk

Origin

Post Office

PlusNet

Phone Co-Op

Pulse8

Radius Communications

Red Matter (Natterbox)

Redcentric

Resilient PLC

RingCentral

Simwood

Six Degrees

Sky 

Skype

Soho66 

Spitfire

SSE

Suretec

Swiftnet

Syntec

TalkTalk  

Telappliant

Telecom2 Ltd

Telephony Services

Teleware

Telserve

TelXL

Timico

Tipicall

Thus Plc

Unicom

UNO

Utility Warehouse

Verizon UK Ltd

Virgin Media

Vodafone 

Voiceflex

Voicehost

VOIP Unlimited

VoIPtalk

VoIPfone

Vonage

Voxbone SA

Wavecrest 

West

Wightfibre

Xinix

XLN

X-On (Storacall)

Yay Ltd

Your Communications 

Zen Internet