SIP trunking for business,
configured and supported.
Reliable SIP trunking for PBX systems, call center platforms, dialers, and CRM-connected phone systems. Inbound, outbound, and international voice — configured by VoipTower engineering during onboarding. Setup and 24/7 support are included with traffic.
SIP trunking should make business calls easier, not harder.
Companies move to SIP trunking for more control, lower telecom complexity, and better support for modern phone systems. In practice, SIP becomes painful when no one manages the configuration, the routing, or what happens when something fails.
What goes wrong with unmanaged SIP
Poor call quality. Dropped calls. Failed outbound. Unstable inbound routing. PBX connection issues. No failover plan. Weak support from low-cost providers. International routing that breaks at the worst time. SIP configuration that doesn't match the phone system.
What VoipTower does instead
Configures the SIP trunk to match your PBX. Connects DID numbers. Builds routing logic. Tests inbound and outbound flows. Sets failover paths. Provides 24/7 engineering support. SIP credentials with no support is not a service — it's a handoff.
What is SIP trunking?
SIP trunking connects your business phone system to the public phone network using VoIP technology. Instead of traditional phone lines, calls travel over an internet-based voice connection.
A SIP trunk can connect to a PBX, IP PBX, call center platform, CRM-connected phone system, business telephony platform, sales dialer, or support desk system. For most companies, the SIP trunk is the core link between their internal phone system and the outside world.
Inbound SIP trunking
Delivers calls from DID numbers to your PBX, call center, or business phone system. Connected to country and number routing logic.
Outbound SIP trunking
Sends calls from your PBX or dialer through VoipTower's managed VoIP routing to the destination country.
Bi-directional SIP trunking
Inbound and outbound on the same trunk. The most common setup for B2B sales, call centers, and support teams.
Multi-trunk setups
Separate trunks per country, campaign, or platform when traffic separation is required for compliance or operational clarity.
How VoipTower delivers managed SIP trunking.
SIP credentials alone don't solve anything. The service is the configuration, routing, integration, testing, and support around them.
SIP trunk configuration
Configured by VoipTower engineering to match your PBX, dialer, or call center platform. Codec, transport, registration, and authentication aligned with your environment.
DID number connection
DID numbers across 25+ countries connected to the trunk for inbound calls. Local, national, mobile, or toll-free per market.
Inbound and outbound routing
Country, business hours, department, language, campaign, and failover logic. Both directions managed.
PBX configuration support
3CX, Asterisk, FreePBX, IP PBX, and most SIP-capable systems — configured during onboarding, not handed over as documentation.
CRM-connected calling
HubSpot, Pipedrive, Bitrix24, and custom CRM workflows. Call history, caller context, and pipeline activity connected to live voice.
Testing, launch, support
Inbound and outbound testing before launch. Onboarding within 24 hours. 24/7 engineering support after launch — included with traffic.
SIP trunking in real business operations.
Different industries need different SIP setups. Trunk capacity, routing logic, and integration shape depend on how your team actually works.
SIP trunking for call centers
Inbound support, outbound campaigns, international traffic, local caller ID, callback numbers, routing by country or campaign, failover paths, queue and team routing. Cheap SIP doesn't help if calls fail.
VoIP for call centersSIP trunking for B2B sales
Outbound calls, inbound callbacks, local caller ID, DID numbers for target markets, CRM-connected call tracking, routing by sales team or region, international campaigns. Connected to PBX, CRM, or dialer.
VoIP for sales teamsSIP trunking for e-commerce
Customer support, order status calls, return and refund flows, delivery issue routing, supplier communication, country-specific support numbers. Stable SIP helps your team resolve issues faster.
VoIP for e-commerceSIP trunking for logistics
Dispatch calls, driver support, customer delivery updates, branch communication, partner calls, emergency routing, routing by location or region. When calls support operations, reliability is critical.
VoIP for logisticsHow a SIP trunk actually carries a call.
From your PBX to a customer — the path through managed SIP trunking infrastructure.
- Your phone system initiates or receives a call. PBX, IP PBX, call center platform, or dialer — connected to the SIP trunk over the internet.
- The SIP trunk authenticates with VoipTower. Registration, codec negotiation, transport (UDP/TCP/TLS), and IP whitelisting are all configured during onboarding.
- The call enters VoipTower's managed routing layer. Inbound calls arrive on a DID; outbound calls are sent through country-specific voice routes.
- Routing logic applies. Country, business hours, department, language, campaign, agent group, or failover destination.
- The call reaches its destination. Inbound — to your PBX, queue, CRM workflow, or agent. Outbound — to the customer in the destination country.
SIP trunking, DID numbers, PBX, and CRM — how they connect.
A SIP trunk is the delivery channel. It only works when the surrounding pieces are configured correctly. Here's how SIP fits into the voice chain.
DID number → SIP trunk
DID numbers are the addresses customers dial. The SIP trunk is the channel that delivers those calls to your PBX. Without a SIP trunk, inbound DID calls have nowhere to land.
SIP trunk → PBX
The PBX takes calls from the trunk and routes them inside your business — extensions, departments, queues, IVR menus. VoipTower configures the trunk to register with your PBX correctly.
PBX → outbound SIP
Outbound calls from your team or dialer go through the same trunk in reverse. Routing logic picks the right voice route based on the destination country.
SIP trunk → CRM workflow
Calls arriving on the trunk can be tied to CRM workflows through your PBX or dialer integration. Customer context, call history, deal status — surfaced to your team in real time.
Why SIP trunking from VoipTower.
Six reasons businesses choose managed SIP trunking instead of a self-service SIP credentials portal.
Better control over business calls
Connect your existing phone system, manage DID numbers, adjust routing based on real business needs. Not a fixed platform — flexible infrastructure.
International calling, managed
International call routing through reliable VoIP infrastructure. Useful for companies with customers, teams, suppliers, or campaigns across countries.
Connect your existing PBX
3CX, Asterisk, FreePBX, IP PBX, and most SIP-capable systems. Keep your familiar setup; improve the voice connectivity behind it.
Use DID numbers across markets
Multiple DID numbers from different countries connected to one managed phone setup. Local presence in key markets, managed centrally.
Custom call routing
Routing by country, team, campaign, language, department, or business hours. The setup matches how your team actually works.
Failover, not just primary
Backup routing so calls have another path if one destination is unavailable. Critical for call centers, logistics, and customer support.
SIP trunking by country.
VoipTower operates SIP trunks and managed VoIP routing across 25+ countries. Eight priority markets with dedicated coverage:
🇩🇪 Germany
Inbound SIP from local and national DIDs; outbound to German destinations.
Germany coverage🇬🇧 United Kingdom
020 London, regional, 03xx national, and 080 toll-free DID inbound on SIP.
UK coverage🇫🇷 France
01–05 geographic, 09 national, and 080 toll-free DIDs over managed SIP.
France coverage🇨🇦 Canada
Local geographic and 800/888-series toll-free DIDs over SIP across provinces.
Canada coverage🇵🇱 Poland
Local and national DIDs on managed SIP, operator-aligned setup.
Poland coverage🇨🇿 Czech Republic
Local geographic and national DIDs on SIP.
Czech Republic coverage🇿🇦 South Africa
Geographic and national-format DIDs on managed SIP infrastructure.
South Africa coverage🇦🇷 Argentina
Buenos Aires and regional DIDs on managed SIP.
Argentina coverageFrequently asked questions about SIP trunking.
Direct answers to common questions about SIP, VoIP, PBX integration, and international routing.
What is SIP trunking for business?
How does SIP trunking work with VoIP?
Can SIP trunking be used with DID numbers?
Do I need DID numbers for SIP trunking?
How does call routing work with SIP trunking?
Is SIP trunking good for call centers?
Can SIP trunking work with my PBX?
Can SIP trunking connect to a CRM?
Is SIP trunking better than traditional phone lines?
Is SIP trunking the same as VoIP?
Can SIP trunking support international calls?
How fast can SIP trunking be set up?
Build SIP trunking that fits your business.
Tell us how your calls should work, which countries you need, and what systems you already use. We'll review, qualify, configure, and activate — within 24 hours.