Guidelines

United Kingdom (GB)

Locale Summary
Locale name	United Kingdom
ISO code The International Organization for Standardization two character representation for the given locale.	GB
Region	Europe
Dialing code The dialing prefix used to establish a call or send an SMS from one locale to the given locale.	+44

Reachability Can Twilio complete calls to numbers in this locale?	Inbound Ability to call numbers. Calls are inbound from PSTN to Twilio numbers.	Outbound Ability to call non-Twilio numbers. Calls are outbound from Twilio to PSTN numbers.
Domestic For calls within the locale	Yes	Yes
International Can in-locale numbers be reached from outside the locale?	Yes	Yes
Toll-Free Can in-locale Toll-Free numbers be reached from within the locale?	Yes	Yes
Outbound restrictions Regulatory and/or Carrier restrictions on outbound calls made from Twilio to non-Twilio numbers in this locale	Starting May 15, 2023, for outbound calling to United Kingdom destinations, new Ofcom rules will block calls from caller IDs (From numbers) that are invalid, do not uniquely identify the caller, or do not contain a Telephone Number that is dialable. See Ofcom's Guidance on the provision of Calling Line Identification facilities and other related services.
Outbound requirements Conditions that must be met before outbound calls are allowed from Twilio to non-Twilio numbers in this locale	N/A
Best practices Useful tips for best performance on outbound calls to non-Twilio numbers in this locale	N/A

Caller ID Can Twilio complete calls to numbers in this locale?	Inbound Inbound call receives originator's Caller-ID. Calls are inbound from PSTN to Twilio numbers.	Outbound Outbound call preserves sent Caller-ID. Calls are outbound from Twilio to PSTN numbers.
Domestic For calls within the locale	+E.164	Local
International Can in-locale numbers be reached from outside the locale?	E.164 (Non-guaranteed)	+E.164
Toll-Free Can in-locale Toll-Free numbers be reached from within the locale?	+E.164	Local

DTMF	Inbound Inbound call receives DTMF from PSTN. Calls are inbound from PSTN to Twilio numbers.	Outbound Outbound call sends DTMF to PSTN. Calls are outbound from Twilio to PSTN numbers.
RFC.2833 format Is RFC.2833 DTMF format supported?	Yes	Yes

Emergency Calling Calls are outbound from Twilio to Emergency (911/933) numbers.	Outbound Ability to make Emergency Calls. Calls are inbound from PSTN to Twilio numbers.
Emergency services Are calls to Emergency Services Numbers in the locale allowed over Twilio?	Yes

For the benefit of all our customers, these guidelines are provided to help you comply with applicable requirements and to help ensure Twilio's platform remains compliant with global telecommunications ecosystem requirements. These guidelines represent our current understanding of common compliance requirements generally applicable to Twilio and its customers, and do not constitute legal advice. By posting these guidelines, Twilio makes no assurances regarding the legal compliance of your application built using our APIs. You are expected to understand and abide by all compliance obligations applicable to your specific application. You should check these pages regularly for updates as telecommunications ecosystem requirements continue to evolve and change, and the information below may be updated or changed without notice.