Understanding the SIP Trunk
A SIP trunk (Session Initiation Protocol) is a virtual telephone connection that links your PBX (IP phone system) to the public telephone network (PSTN) over the Internet. It replaces traditional analogue or ISDN lines.
How does a SIP trunk work?
The SIP protocol handles the setup, modification and termination of calls. When one of your employees dials an external number:
- Your PBX sends a SIP
INVITErequest to the WebTic server - WebTic routes the call to the destination telephone network
- Voice is carried in real time via the RTP protocol (Real-time Transport Protocol)
- Billing is per second or per minute depending on the plan
Advantages over traditional lines
- Lower cost: rates well below traditional carriers, especially for international calls
- Scalability: add channels in a few clicks, with no installation delay
- Geographic flexibility: local numbers available in many countries
- HD quality: G.722 codec for superior voice quality (depending on equipment)
- Redundancy: automatic failover to a second trunk in case of outage
SIP Trunk vs Cloud PBX
The SIP trunk connects to your PBX (which you manage). This is different from a Cloud PBX, where the entire infrastructure is hosted by the provider. A SIP trunk is ideal if you already have a 3CX or FreePBX in place.
WebTic offers
WebTic offers SIP trunks with:
- Calls to Switzerland, France, Belgium and Luxembourg at reduced rates
- Included: DID numbers in several countries
- Simultaneous channels: from 2 to unlimited
- WebTic uses all reasonable means to ensure service availability, excluding planned maintenance announced in advance
