T4Com SIP Trunking review

T4Com takes the pain out of VoIP, with a slick managed service that’s good value and easy to use

IT Pro Recommended
  • Setup and management is taken care of; Good value;
  • Changing IP address of SBC means handsets con't connect;

Those who don't have the time or expertise to set up their own PBX will love T4Com. This UK-based SIP trunking specialist can look after it all for you. Just give the company your requirements and it will supply a complete VoIP system tailored to your needs.

T4Com's SIP-trunking services operate from its London data centre; you can connect using your existing broadband connection, or have T4Com install a VoIP-optimised circuit. Whichever option you choose, you receive free calls between all offices connected via T4Com SIP trunks, and if an office is relocated, all its VoIP services will be transferred seamlessly to the new location.

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When it comes to phone numbers, the choice is yours. T4Com can port your existing PSTN, ISDN or VoIP numbers over to the new service, or issue new ones. These can be specified in ranges, and can be local to office locations in the UK or anywhere else in the world.

T4Com uses 3CX as its PBX, and you can opt to have the service cloud-hosted and managed by T4Com, or installed locally. Fees are low - each SIP channel costs 4 per month, with a hosted PBX adding 5 per extension to your monthly bill.

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We chose a cloud-hosted 3CX PBX, and T4Com provided us with Yealink T23G VoIP handsets for testing. Costing around 62 each, these offer an excellent range of call features and are easy to use. However, if you want another brand, T4Com can provide any IP handset that's certified to work with 3CX.

The only other piece of hardware that had to be installed in our lab was the 3CX session border controller (SBC). Inside this palm-sized black box you'll find our old friend, the Raspberry Pi - here set up to simplify firewall configuration by creating a tunnel to deliver SIP and RTP packets to our remote PBX.

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With all this in place, we had to add only a forwarding rule on our firewall for port 9090 and the SBC. Since our phones had already been provisioned and assigned to extension numbers, we could then use them straight away. A word of warning, though: agree a fixed IP address for the SBC beforehand, since handsets are supplied preconfigured to register with this address, and they won't be able to connect if you change it during installation.

Apart from SIP trunks and inbound and outbound call rules, all key PBX features are available in the 3CX portal via remote access. We could create a company phonebook, set up a digital receptionist for inbound call handling and much more. If you don't want to get your hands dirty, you can ask T4Com to do it for you as part of the service.

Once our account was set up, we received an email from T4Com detailing our services, extension numbers and so on. The message also provided links to the 3CX softphones for Windows, OS X, Android and iOS, along with attachments containing softphone configuration files.

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After we'd installed the softphone on Windows 7 and 10 systems, a simple double-click on this file automatically configured them to use the 3CX PBX with their relevant extension. The same mail attachment also successfully configured the iOS softphone on our iPad, so in less than a minute, we could make phone calls from anywhere, pick up voice messages, view our call log and remotely access the company phone book.

Small businesses worried about VoIP installation and potentially having to deal with management headaches can rest easy with T4Com at the helm. This managed service does it all for you, and its monthly fees are reasonable, too.


Small businesses worried about VoIP installation and potentially having to deal with management headaches can rest easy with T4Com at the helm. This managed service does it all for you, and its monthly fees are reasonable, too.

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