A practical brief for international calls, internet voice and Microsoft Teams. Official references checked 30 October 2026; service terms and availability must be confirmed for your actual requirement.
Compare a calling pattern, not a headline.
List the countries and number ranges you call, split mobile from landline traffic, and gather a representative month of usage. A useful quote identifies included destinations, excluded ranges, per-call setup charges, minimum duration, billing increments, monthly fees and tax treatment.
Compare the same number of minutes across the same period. Include hardware, setup, number transfer, licence and exit costs where relevant. A cheaper rate can still produce a larger total if the rest of the service does not fit.
The homepage planner is a transparent arithmetic example. It does not look up a rate, identify a carrier, verify an offer or guarantee a saving. We make no independently verified claim to the lowest rate across the market.
VoIP is the way the voice travels.
Voice over Internet Protocol carries calls over an IP connection. The service may use a phone, an app or a business calling platform. The right question is what your service must do: users, numbers, devices, international destinations, accessibility and support.
Power and connectivity are part of the service. Digital phones can stop working during a power cut without appropriate backup. Discuss emergency calling, location information, alternative communications and any alarm or telecare equipment with the proposed provider before a change.
A SIP trunking review starts with the existing PBX or communications platform, concurrent call requirement and the numbers to be retained. Check interoperability, network configuration, inbound and outbound routes, resilience, security and how usage will be charged.
Do not assume that a generic SIP trunk connects directly to Microsoft Teams. A Teams design has specific connectivity and infrastructure requirements. Test the proposed route before a production migration.
Teams Phone. Licensing plus connectivity.
Microsoft documents four PSTN options: Calling Plans, Operator Connect, Teams Phone Mobile and Direct Routing. Different parts of an organisation may use different arrangements. Geography and operator availability affect the choice.
Teams Phone provides business telephony capabilities; external calling also needs a suitable PSTN arrangement. Your Teams plan, add-on entitlement, user types and selected connectivity must be checked together. Meeting dial-in or Audio Conferencing is not a substitute for a complete user calling design.
Direct Routing connects telephony infrastructure through a Microsoft-certified Session Border Controller. Plan licences, DNS, certificates, network access, dial plans and voice policies, then validate calls. It can suit an existing carrier or PBX requirement, but is not automatically the simplest route for every organisation.
These links are product references, not a Microsoft endorsement or a claim that Dial the World is an accredited partner.
Make the change a considered one.
Inventory the numbers, authorised account holders, users and existing services.
Agree number retention and the correct provider-led transfer process before cancellation.
Check linked broadband, devices, alarms, telecare and business workflows.
Test call quality, caller identity, inbound routing, international destinations and agreed emergency arrangements.
Define the migration window, service owner, support route and rollback or recovery plan.
Do not send account passwords, payment details, tenant-admin credentials or switching codes through the public enquiry form. Begin with a non-sensitive requirement.