What are SIP best practices?

The Session Initiation Protocol (SIP) is a cornerstone in Voice over Internet Protocol (VoIP) transmissions. The underlying network equipment is complex and supports a wide range of functions that sometimes conflict. Consequently, businesses find themselves deploying less than optimal solutions. What follows are tips that help your business maximize its SIP investment.

What is SIP?

SIP is the brain that drives VoIP connections. The technology powers all VoIP phones, devices, and applications and performs tasks, like registering devices, maintaining call presence and overseeing call audio. The specification was designed to be open, so different suppliers’ hardware and software can be integrated more easily.

The SIP market has reached critical mass yet continues to showcase healthy growth. The global SIP trunking services market size was $6.88 billion in 2017 and is projected to reach $12.70 billion in 2023, a Compound Annual Growth Rate (CAGR) of 10.7%.

You’ll want to ensure that all VoIP calls occur with as few interruptions as possible. Consequently, you need to account for issues, like available network bandwidth, latency and stability. The following tips improve inbound and outbound call quality and ensure needed VoIP connectivity for employees, partners and customers.

1. Choose a supplier with high-bandwidth capabilities

VoIP is a shared service where a number of individuals transmit information over common communication lines. The services support broadband transmissions with rates ranging from a few Mbps to hundreds of Gbps.  

A VoIP design should include plenty of extra bandwidth headroom if network utilization expands – which it typically does. Corporations find new uses for these systems as they become more familiar with them. Usually, organizations base their network selections on about 75% usage of the allotted bandwidth at peak periods and bandwidth upgrades occur every few years.

2. Use wired Ethernet connections wherever possible

Wireless connections have become quite popular because they allow individuals to roam from place to place but still have network service. However, these links are susceptible to interference that can cause data packet loss and jitter–noise on a line. Latency and packet loss are not usually noticeable through casual browsing, but it can affect VoIP calls, with calls breaking up or being dropped. Try to limit your wireless connections only to those applications where wired options are not feasible.

3. Prioritize network traffic

The IP protocol allocates bandwidth on a first-come, first-served basis. As network traffic grows, contention often arises. You’ll want to make sure that your users have the bandwidth needed to complete their work and that traffic is available for important applications.

Quality of Service (QoS) is a feature that takes the randomness out of IP links and assures that bandwidth is available for certain applications. The user prioritizes which applications require bandwidth. The system provides the bandwidth by taking steps, like preventing bandwidth intensive applications, such as HD video applications, from negatively impacting the key  applications’ performance.

4. Keep your firmware updated

Change comes quickly nowadays. A new threat emerges in the morning and by afternoon, a fix is available. Consequently, you need to be proactive in checking your network hardware manufacturers’ firmware upgrades. They are sent out on an as-needed basis and include patches for security and performance issues. In some cases, you’ll need to manually update the system via the Command Line Interface (CLI) found on commercial routers.

5. Establish a strong security profile

All businesses are vulnerable to cyber threats. Therefore, it is vital to protect your business data from cybercriminals who target individuals and businesses of all sizes. When setting up network equipment, make sure that they comply with your corporate security architecture, so users are properly authenticated. No company wants outsiders listening in on conversations, especially when sensitive information is shared over the phone.

6. Implement ring groups 

With VoIP, you gain the ability to have multiple phones answer an incoming call. However, you won’t want your president’s phone ringing every time an outsider calls. Ring groups is a way to route incoming calls to those individuals within a department who can address the needs of the caller. This feature is often used in the customer service department. Once a call reaches that area, the call can go to anyone available rather than just one specific person. To deploy that feature, you need to set up a hunt pilot that identifies everyone who could take the call.

7. Improve Voice Quality  

The SIP Application Layer Gateway (ALG) is a feature found in network routers to improve performance and add security features (mainly a firewall) to prevent outsiders from entering the network. Routers segment your internal network from that of your carrier through a process known as Network Address Translation (NAT). Here internal network traffic is translated to the proper internet IDs. An ALG acts as a proxy and rewrites the destination addresses in data packets for improved connectivity.

However, the translation can create these conflicts that negatively impact voice quality:

• One-way audio (only one person can hear the other)
• Phones don’t ring when called
• Calls drop after being connected
• Calls go straight to voicemail for no known reason

As a result, some VoIP traffic is lost between the phone and the VoIP service provider. Certain commercial routers are smart enough to inspect the SIP messages themselves and leave private IP addresses alone, but many routers default to ALG, and voice quality suffers.

So, to fix these problems, you’ll need to disable SIP ALG. Log into the router and turn the function off. More advanced corporate firewalls may require further adjustment, such as port forwarding.

VoIP is an emerging technology with great potential. Deploying such a network is a complex process with many contingencies. You’ll need to deploy a lot of bandwidth, opt for wired connections where possible, keep your connections secure and disable ALG to ensure that your networks are optimized for VoIP connections.