VOIP & SIP BASICS

What is VoIP?

Voice over Internet Protocol (VoIP) is the technology that lets you make and receive calls over a broadband internet connection instead of a traditional copper phone line. Your voice is digitised and sent as data packets across the internet, so the same connection can carry calls, voicemail, video and messaging at once. Because it’s far more bandwidth-efficient and cheaper to run, VoIP is now the default for business telephony — today virtually every new PBX deployed worldwide is VoIP-based, and most SIP providers, including Sip Systems, deliver low-cost calling this way.

What is SIP?

SIP (Session Initiation Protocol) is the open signalling standard that sets up, manages and ends VoIP calls. It’s text-based, scalable, and quick to implement, with no special handling required at the network level. Because it’s a peer-to-peer, vendor-neutral standard, you can join a session from almost any device — a desk phone, a softphone on your laptop, or a mobile app — wherever you happen to be. That flexibility is exactly why SIP underpins modern business phone systems.

FREQUENTLY ASKED QUESTIONS

How do I start making calls from my PC?

Register a free account.
Download and install one of the recommended softphones below.
In your account, open SIP Devices and create a new device with your Caller ID.
Enter the hostname, username and secret from that device into your softphone.
Dial numbers in full international format — there’s no need to add a leading “+”.

How much does it cost?

Registration is free, and you receive free test credit the moment you sign up.
Use your own numbers as Caller ID at no charge.
Outgoing calls are prepaid at our low call rates — no contracts, no line rental.
Special pricing is available for call centres and partners.

How do I configure my VoIP equipment?

We support the ulaw, alaw, ilbc, gsm, g723, g726 and g729 codecs.
RTP media uses UDP ports 10000–20000.
SIP registration is on port 5060 (UDP).
If you run a firewall, whitelist only voip.sip-systems.com.
Stuck? Email support@sip-systems.com and our team will help.

Do you have an Asterisk / FreePBX trunk example?

Use these peer details as a starting point for a SIP trunk:

type=friend
username=XXXXXXXXX
secret=AAAAAAAAAA
fromuser=XXXXXXXXX
host=voip.sip-systems.com
context=from-trunk
disallow=all
allow=alaw&ulaw&gsm&g729
insecure=port,invite

The same SIP credentials connect to any Asterisk or FreeSWITCH based system, IP phone or softphone.

Where do I manage my account and credentials?

Log in to your account at any time. We strongly recommend storing the credentials the server generates at signup somewhere safe. You can review or update your details under My Profile — and you’re always welcome to contact support@sip-systems.com for help connecting your account.