Number of extensions

Handsets

There are typically four types of handset: basic, standard, advance/reception phone, wireless (DECT). The more advanced phones provide more buttons for speed dialing - a real time saver in a busy office. In addition you can add a wireless headset to most office phones.

Number of phone lines

Although you might have 10 extensions, it is unlikely that everyone will be on the phone at the same time. For this reason you will require fewer phone lines to and from your office. Consider how many concurrent phone conversations happen in your office during busy periods, and add a line or too extra for growth.

Voice mail

You should consider the need for voicemail. In today's business environment, many customers and suppliers expect that they can leave a message directly with the person they want to speak to.
Also voicemail is more secure, more efficient and more reliable than asking others to take messages.

Music on hold

If you have customers calling in then music on hold makes your company appear more professional. You can also use specially recorded music and company promotional material.

Cabling

Cabling is an essential part of any phone system implementation. Many companies make the mistake of under-specifying the quantity and location of phone sockets. Where possible invest in professional CAT5 cabling with a central patch panel and plenty of network points (sockets). This is flexible and can be used for voice and data. By not planning for the long term you will end up with an expensive recabling exercise sooner than you think.