What is a SIP number?
A SIP number is a normal phone number whose calls are delivered over the internet using SIP, the standard protocol behind softphones, office phone systems and call centers. People dial it like any other number; you answer it on any SIP-capable app or device.
What SIP means
SIP stands for Session Initiation Protocol. It's the open standard that phone apps and phone systems use to set up, ring, answer and end calls over an internet connection.
Because it is a standard, you are not locked into one app. Any SIP-compatible softphone, desk phone or PBX can register with the same account.
How it works
When someone dials your number from a mobile or landline, the call reaches your provider over the regular phone network. The provider then delivers it over the internet to whichever device is registered with your SIP account.
Your app registers using three details: the SIP server address, a username and a password. Once registered, the app shows as online and the number rings there. Outgoing calls work the same way in reverse.
What you can connect
- Softphones: Zoiper, Linphone, MicroSIP, Bria and other SIP apps on Windows, macOS, Android and iOS
- Office phone systems: 3CX, FreePBX, Asterisk and similar PBX software
- Call-center and helpdesk setups that support SIP trunks or SIP accounts
- Hardware desk phones that support SIP
- Your ordinary mobile or landline, via call forwarding
Connect a softphone in 3 steps
- Open your number's page in the ZuteSIP dashboard and copy the SIP server, username and password.
- In your softphone, add a new SIP account and paste the three fields exactly as shown.
- Save. The status turns green or 'registered' when it's connected, and calls to your number ring the app.
Connecting a PBX
In a PBX such as 3CX, FreePBX or Asterisk, you add the number as a SIP account or trunk using the same server, username and password. You then route incoming calls to an extension, ring group or IVR menu, and choose which outbound calls use this number.
This lets a whole team share one public number, with calls distributed to whoever is available.
Who uses SIP numbers
Remote teams use a SIP number so everyone can answer the company line from a laptop, wherever they are. Small businesses connect one to a PBX to get extensions, ring groups and a menu without installing phone lines.
Individuals use SIP too: a softphone on a laptop is a convenient way to take calls on a foreign number while travelling, without swapping SIM cards or paying roaming charges for incoming calls.
Developers and IT teams like SIP because it's an open standard. They can test call flows in Asterisk or FreePBX and move between apps or systems without changing the number.
SIP number vs mobile SIM
- Location: a SIP number works anywhere you have internet; a SIM depends on local coverage and roaming
- Devices: a SIP account can be registered on several apps; a SIM lives in one phone
- Team use: a SIP number can ring a PBX and several people; a SIM rings one person
- Continuity: a SIP number isn't lost with a broken or stolen phone
Can a SIP number receive SMS?
SIP itself is mainly about voice calls, and many SIP apps don't handle text messages. With ZuteSIP, SMS to your number arrive in the online dashboard in real time, separately from calls, so you get both without extra setup.
Troubleshooting registration and calls
- Won't register: re-copy the server, username and password; a single extra space is a common cause
- Registers but doesn't ring: check that only the intended device is set to answer, and that the app is allowed to run in the background on mobile
- One-way or no audio: often a router or firewall issue; try another network, or enable the app's NAT or STUN option
- Mobile app misses calls when idle: enable push notifications or keep the app active, depending on the app
- Simplest fallback: turn on call forwarding to your normal phone while you debug
What's included with a ZuteSIP number
Every ZuteSIP number includes SIP credentials, call forwarding to any phone, a browser dialer, unlimited incoming calls and SMS, and 500 outgoing SMS plus 1,000 outgoing minutes a month. Plans start from $1.80 per month, billed yearly ($21.60 per year), in any of 181 countries.
If the number hasn't been used for any call or SMS, you can get a full refund within 7 days, and you can keep it for as long as you want.
Included on every plan
- Unlimited incoming SMS
- Unlimited incoming calls
- 500 outgoing SMS per month
- 1,000 outgoing minutes per month
- SIP credentials, call forwarding and web dialer
- Keep your number as long as you want
- 7-day money-back guarantee if the number is unused
Numbers from $1.80 per month, billed yearly ($21.60 per year). Pay with USDT or USDC.
Frequently asked questions
Do I need special hardware for a SIP number?
No. A free softphone app on your computer or phone is enough. SIP desk phones and PBX systems are optional.
Can one SIP number ring several devices?
Yes. Register the same SIP account on multiple apps, route it through a PBX, or combine SIP with call forwarding.
Can a SIP number receive SMS?
ZuteSIP numbers receive SMS in your online dashboard, separately from SIP calls.
Is a SIP number a real phone number?
Yes. ZuteSIP numbers are real numbers on national networks. Anyone can call them from a normal phone; SIP is just how the calls reach you.
What details do I need to set up SIP?
Three: the SIP server, your username and your password. All three are shown on your number's page in the dashboard.
Which SIP apps work?
Any standard SIP client, including Zoiper, Linphone, MicroSIP and Bria, and PBX systems such as 3CX, FreePBX and Asterisk.
Why do I have no audio on SIP calls?
Usually a network or firewall issue. Try a different network or enable NAT or STUN settings in your app.
Related guides and use cases
- How to get a phone number in another country
- How to verify WhatsApp without a SIM card
- Receive SMS online: free public numbers vs a private number
- How to get a US phone number from outside the USA
- How to get a UK phone number from abroad
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