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VoIP Phone System Setup with Issabel

An old analog PBX needs new wiring and extra line cards for every extension, and it can't reach your other branch. Our VoIP setup moves office phones onto the data network using Issabel or Asterisk. Carrier lines connect through a gateway, and branches call each other over an internal trunk with no carrier charges.

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Tools & technology voip
  • Issabel
  • Asterisk
  • FreePBX
  • Grandstream
  • Yealink
  • SIP Trunk
  • FXO Gateway
  • Zoiper
  • Fail2ban
5work areas
4deliverables
4steps

What is VoIP Phone Systems?

VoIP setup for business means moving the company phone system onto the existing data network, using an IP PBX such as Issabel or Asterisk in place of an analog PBX with line cards and extra wiring. It fits companies whose old PBX has no room for new extensions, that lose customer calls when everyone is busy, want sales calls recorded, or pay for calls between branches. PikoSystem writes the internal dial plan, installs Issabel on dedicated hardware or a VM, configures extensions, IVR, call queues and call recording, connects carrier lines through an FXO gateway or SIP trunk, and adds a voice VLAN and QoS so calls stay clear. You get an extension and inbound routing table, a configuration backup, a short user guide and admin access to the Issabel panel.

When you need VoIP Phone Systems

  • Our old PBX is full and there's no room for new extensions.
  • When everyone is busy, customer calls just get lost.
  • We want sales calls recorded.
  • We have a second branch and calls between offices cost money.

What VoIP Phone Systems includes

01

Needs review and dial plan

We map extensions, carrier lines, departments and inbound call flow, then write the internal numbering plan.

02

Issabel install and config

Issabel or Asterisk is installed on dedicated hardware or a VM, with extensions, IVR, call queues and call recording configured.

03

PSTN lines and SIP trunks

Analog lines connect through an FXO gateway, and E1 lines or carrier SIP trunks connect directly to the server.

04

Desk phones and softphones

We configure IP desk phones and set up softphones on mobiles or laptops for staff outside the office.

05

Call quality and security

A voice VLAN and QoS on switches and routers keep calls clear when colleagues download large files. SIP ports are closed or restricted on the internet side.

What you get from VoIP Phone Systems

  • Extension, group and inbound routing table
  • Phone server configuration backup
  • Short user guide for phones and call reports
  • Admin access to the Issabel panel

VoIP Phone Systems: a practical guide

Issabel, FreePBX or 3CX?

All three sit on Asterisk or a similar engine; the differences are the admin panel, licensing model and operating system. Issabel is free, includes a call center module and has a large Persian-speaking community. Version 4 runs on CentOS 7, which reached end of life in 2024, so new installs should use Issabel 5 on Rocky Linux.

FreePBX is also open source, with optional commercial modules. 3CX is easier to install and has a polished mobile app, but it is licensed by concurrent calls. For most companies looking at an IP PBX, Issabel 5 is a sensible default.

Connecting PSTN lines: FXO gateway, E1 or SIP trunk?

An FXO gateway uses one port per analog line. Caller ID type and busy tone detection must match the carrier, or caller numbers won't show and lines stay busy after a call ends. With more lines, an E1 carrying 30 channels through a gateway or card is usually more practical.

A carrier SIP trunk needs no wiring and capacity changes by contract, but it depends on a static IP and a stable internet link. G.711 sounds better and uses about 87 kbps per call; G.729 needs around 31 kbps, but transcoding adds CPU load on the server.

Common business VoIP setup mistakes

One-way audio is the classic. Usually SIP ALG is enabled on the router, or the RTP port range, 10000 to 20000 by default in Asterisk, isn't forwarded through NAT. On MikroTik, disable the sip service port.

Extension passwords equal to the extension number, port 5060 open to the internet without Fail2ban, and international dialing allowed for every extension invite toll fraud. Without DSCP EF marking, switches and routers can't prioritize voice. PoE budget for desk phones and disk space for call recordings also need planning from day one.

Call queues and recording: what shapes the server?

Queue strategy decides which agent gets the call. ringall rings everyone at once, leastrecent picks whoever has been idle longest, and fewestcalls spreads load by call count.

If every call is recorded, decide on disk space and retention up front; WAV files are much larger than MP3. Concurrent calls, codec transcoding and call center reporting then set the CPU and RAM the server needs.

How VoIP Phone Systems works

  1. 01

    Needs review

    In one meeting we go through departments, lines and call scenarios with you.

  2. 02

    Plan and hardware list

    You receive the dial plan, gateway and phone models and a work estimate.

  3. 03

    Install and cut over

    We bring up the server and phones. Carrier lines are moved at the hour with the fewest calls.

  4. 04

    Test and training

    We test internal, inbound, outbound and recorded calls and train your receptionist and IT contact.

VoIP Phone Systems: frequently asked questions

Can Issabel run on a virtual machine?

Yes. With SIP trunks and IP phones, running it on Proxmox or VMware works fine. If you need analog or E1 cards inside the server, we recommend dedicated hardware or an external gateway.

Can an IP PBX work alongside our existing PBX?

Yes. The current PBX can connect to the VoIP server through a gateway, and extensions can move over in stages. This suits companies that don't want to replace every phone at once.

How do you keep a VoIP system secure?

Attacks on SIP ports and toll fraud through international calls are common. We set strong extension passwords, Fail2ban, IP restrictions and block call routes you don't need.

Related searches

  • Issabel setup
  • IP phone system
  • IP PBX
  • business VoIP
  • Asterisk PBX
  • Issabel call center

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