SIP Trunking

SIP trunking provides access to and from the Public Switched Telephone Network (PSTN) over the Internet Protocol (IP). Unlike in traditional telephony, where physical wires were once delivered from the telecoms company to a business, a SIP trunk operates over an existing broadband or leased line allowing a company to replace their traditional fixed PSTN lines with PSTN connectivity via a SIP trunking service provider, such as O-Tel Telecom.

How it works SIP Trunks are linked to a customer’s current telephone system which is either an IP enabled PBX or by using a Media VoIP Gateway, typically, a more traditional PBX. Outgoing calls are then routed through the PBX and out via the SIP Trunk instead of using costly traditional phone lines.

The Benefits

SIP trunks offer significant cost-savings eliminating the need for costly analogue, ISDN BRIs (Basic Rate Interfaces) or PRIs (Primary Rate Interfaces). SIP trunks offer the flexibility of being able to route multiple calls from your existing local numbers, anywhere in the world, to any national or international number within your company at the same cost. So a call to a Cape Town number may be answered in London or NewYork. SIP trunks allow home workers to be connected to the main office using the internet allowing transparent customer communication. SIP trunks can connect intraoffice PBXs eliminating the cost of intra office calls and offering the flexibility of overflowing calls to other offices at peak times or out of hours.

Billing and Costing

* Integrated pre/postpaid real-time billing and costing engine with call cut off* Unlimited customizable charge plans for your clients (wholesale model).* Blocked, flat rate, single rate and multi-tier rating (vary rate based on call duration)* Costing by ANI, NPA, NPA+NXX, DNIS, time of day, day of week, date/time range and/or destination* Ability to vary the scale of a minute at different intervals of a call.

Real-Time Control and Monitoring

Today’s competitive climate demands that businesses conduct their operations in real-time especially when it concerns network security, credit validation, rating and billing. O-Tel Telecoms Trunking solution helps to make your business more efficient and successful by performing its core functions in real-time resulting in improved cash flow and reduced collections, fraud and administrative overhead. Airtime replenishment can be done 24/7/365 securely via EFT. The world class automated system will ensure your service is one step ahead of the competition.

Multi-Vendor Device Support * Gateways * Softswitches * Session Boarder Controllers * Proxy Servers * Softphones, * SIP phones, and * IADs

Reporting * Centralized Reporting Engine to allow reports to be managed from within the portal * Includes Live Call Flows

Free Trial We believe that the full benefits are better demonstrated than written and therefore offer a 30 day no obligations free trial to illustrate the benefits.

NOTICE: Due to unprecedented growth in our Channel Partner Program, O-Tel Telecoms can no longer accept new subscribtions for Retail, SME, and Corporate Clientele. We can refer your query to our Nationwide Partner network, whom are very capable of assisting in your VoIP Project. Please click here to submit your query and a partner in your area will contact you soon.

SIP Trunking

Take advantage of our low cost SIP Trunk line rental and call charges which are compatible with all types of telephone system that can use SIP Trunks.  Whether you need a VoIP telephony service for your Asterisk or VoIP Gateways connected to your Legacy (Analog) PBX, or need to utilise the VoIP capabilities of your Panasonic, Siemens, Avaya, Samsung, LG, Toshiba or other brand of phone system then our business quality SIP trunking services are for you.   Even if you don’t have a VoIP compatible phone system you can still take advantage of our low rates and line rental by installing a VoIP gateway which will allow you to route calls from your phone system across the internet to our SIP Trunk service.  For small business users with Analogue or ISDN BRI telephone lines you can connect any popular VoIP gateway which offers VoIP G729 connectivity for SIP Trunks as well as branch office connectivity for free calls between offices.

Free Calls

Provided another branch is using an O-Tel SIP service, the call will be free of charge.

Porting Numbers

Using SIP trunking, if you decide to move offices, you can take your Telkom telephone number with you. This is major benefit of the service. For example, if you are located in Durban with a 031 number, and move to Cape Town, you can keep your current telephone number by Porting it to our VoIP network and using SIP Trunks.

Number Provisioning

A major benefit of using SIP Trunks is the ability to use geographic phone numbers for most South African exchanges, either from your present location or numbers from exchanges around the country. For example, you are based in Bloemfontein and require a local presence in Johannesburg, Pretoria and Cape Town. You will be provided with 051, 010, 012, and 021 numbers. The calls from these destinations will be routed to you via your broadband connection. The good news for you is you will not require 0860 or 0861 numbers, and your customers will not have to pay the inflated rates for dialling 0861, and 0860 numbers.

Why SIP Trunking ?

SIP Trunking provides the ability to make and receive telephone calls over the internet. Within the next 10 years, 90% of telephone calls world wide will be made over the internet. SIP is a world wide internet protocol for establishing and maintaining multi-party, mixed media sessions over converged networks. SIP enables the creation and deployment of feature rich services that go far beyond simple VoIP calls. SIP provides an open programming protocol for voice, text and video applications. SIP is the signalling protocol which allows mixed-media sessions of text, voice and video applications using existing devices, including PC/laptops, PDA’s and future smart phone technology.   At the residential end of the market, companies such as Skype have had 100 million downloads of their software; millions of people are making free calls between friends and family over the internet across the world.   As the commercial version of the residential product, SIP trunking is more resilient and will interconnect with the present voice networks worldwide.   SIP trunking has the full backing of Ofcom (the telecommunications governing body) which has allowed more flexibility compared to the present voice network.


Can I use my present broadband connection?

This depends on the size of your broadband and how many simultaneous calls you want to make over the connection.  The size of a SIP voice call is 20Kbitps, so if you have an upload of 256Kbitsps, you could have 12 calls (without any additional data) over one dedicated connection.

How do I port my numbers?

There is a simple form to be completed which we then send to Telkom, the process takes 14 working days.

Can I discontinue my present lines?

We would always recommend you keep a percentage of your analogue or ISDN telephone lines as back up.  In the event of your broadband connection going down, we will route calls to an alternative telephone number/s.  Most VoIP Phone systems are configured to use existing Analogue and ISDN Telephone Lines as well as SIP Trunks.

Are there any setup charges?

Some services have FREE set up and other SIP trunk services have a small set up charge.  To get details of the services we provide and their set up and rental charges, it will be listed on each services SignUp page.

Do I need to change my telephone System ?

Many new telephone systems will support SIP trunks; we have tested, and are approved by most manufactures.  We can provide conversion units (VoIP Gateways) which connect to your existing telephone system to convert analogue / ISDN trunks to SIP Trunks.  This will allow you to take advantage of SIP Trunks and VoIP Calls without upgrading your current telephone system.

How Resilient is the VoIP network?

The major benefit of the internet is there is no single point of failure. As a company, we have equipment based in separate locations, should one connection fail the call will be automatically routed to an alternative location.


Up and running in minutes!

We are a licensed carrier-grade wholesale VoIP provider offering high-quality SIP trunking and DIDs (phone numbers) at the most competitive rates. Our service is very flexible and scales down from the VoIP hobbyist, up to the largest call centers. When you sign up for account with us, you receive immediate access to the best management panel on the market to get your calls live within minutes. You will have the ability to purchase DiDs (numbers), manage trunks, view call records in real time, review statistics, and more.

How does O-Tel’s Billing work?

We run a prepaid service where you must keep a positive account balance to avoid service interruption. You can purchase services and airtime 24/7/365 via secure EFT while logged into your O-Tel Client Area.

Outbound Traffic

We have designed our plans around a no nonsense policy that we hold near and dear. There’s no contract. We have thoroughly gone through or system to ensure that our plans will give you the ultimate flexibility and the best price.

What protocols do you support?

At the moment we only support SIP.


Our state of the art system allows you to purchase and manage your DIDs. You have the ability to purchase single DIDs as well as DID blocks. The VoIp Control panel you to manage and customize thousands of DIDs with ease.

What areas/provinces can I purchase DiDs in?

O-Tel has National DiDs thanks to its nationwide  service deployment. O-Tel’s current offering included the major cities codes, such as 010, 012, 021, 031, 041 and 051. Other number codes include 013, 014, 015, 016, 017, 018, 022, 023, 027, 028, 032, 033, 034, 035, 036, 039, 043, 044, 045, 047, 053, 054, 056, 057, and 058.

Can I Port number to O-Tel?

Yes, we allow ports. Port orders into O-Tel are R179 for single-number orders. Port orders with up to 100+ contiguous numbers are R79 per number plus R699 admin fee. You will find the online Porting Application here:

Does O-Tel pass Caller-ID?

We pass Caller-ID, but do not guarantee successful transmission. We are able to transmit Caller-ID to all parts of South Africa as well as to some international destinations.

How do I set the Caller-ID I wish to transmit?

We transmit Caller-ID based on the presence of one of the following header fields in order of preference: “P-Asserted-Identity”, “Remote-Party-ID” or “From:”.

Can I call Telkom 0800, 0860, 0861, 102x and 10111 numbers using your service?

Yes, we can terminate calls to these numbers via cross connect.

Do you sell or give out personal information of our customers?

No, we take our customers’ privacy very seriously and do not release customer information unless we are legally required to do so. We abide by DoJ’s requirements, and RICA.

Can I view usage and check my remaining balance?

You can view in-progress calls, call records, and remaining balance in realtime once you’ve logged into your account. An email will also be sent to you once it reaches the warning limit your have set.Does O-Tel offer postpaid service?No, at this time our services are all strictly prepaid.

What dialing format should I use when sending calls?

For ease of use, we have kept the dialing codes as standard local, that is [area code][number]  (011-xxx-xxxx ). For international dialing, add 00, then the country code. EG: To London,UK  00-44-208-xxx-xxxx

How many concurrent calls can you support?

Our state of the art carrier-grade platform can handle bursts of thousands of calls per second. We separate the signaling streams and send your media directly to our gateways throughout our national network so that you experience the lowest audio latency possible.

Does O-Tel have any tools to prevent against fraud?

Yes, we allow our customers to set a maximum outbound limit for calls. We also advise that you follow some general security practices in order to minimize fraud on your account:

  • Ensure your password for your O-Tel SIP Trunk account is very secure.
  • Restrict web access to your PBX/VoIP system.
  • Protect your PBX/VoIP system with software-based firewalls such as IPTables.
  • Protect your network with a hardware-based firewall.
  • Use strong passwords for all phone extensions on your PBX.
  • Use non-standard ports for system services.
  • Implement a VPN for your PBX/VoIP system or join the O-Tel National MPLS ADSL Network.
  • Review access logs on a regular basis.
  • Keep up to date on security patches and practices for your network services.

VoIP fraud patterns are constantly evolving today and we are doing our part to develop increasingly sophisticated detection and prevention measures. The best line of defense is always the security of your own systems.

SIP Trunk Wholesale

TRY IT OUT!! (30 days)
Package Basic10 Basic25s Basic50s Basic100s
# of SIP Accounts 10 Accounts 25 Accounts 50 Accounts 100 Accounts
Billing Mechanism Per Second Per Second Per Second Per Second
Concurrency 100 250 500 1000
Package Basic10 Basic25s Basic50s Basic100s


On-Net Billed per minute
Reseller-Net These are calls within your SIP Accounts
Standard Support Free, Includes Ticket support only
Contact us for pricing!