Account numbering schemes

If your customers will have SIP telephones registered on your system, each telephone line must be assigned an account number. These numbers will be the internal telephone numbers, as well as providing destination for forwarding numbers to. The system will allocate these automatically according to the configuration set by the installer, who will discuss what scheme to use with you. This is a matter of personal preference; you may care to consider the following:

• Some customers like to make account numbers be similar to local telephone numbers in their country to encourage users to think of them as real telephone numbers.
• Other customers prefer to make them different to prevent users confusing them with real telephone numbers.
• The more digits, the more accounts can be supported. For example, 4 digits allow for ten thousand accounts, 6 digits for one million accounts, and 8 digits for one hundred million accounts.
• Any number dialled by a user which is not a valid internal number is considered to be external, and forwarded to a peer according to a route.
• For large systems in the North American Numbering Plan area (USA, Canada, and the Caribbean), 7 digit accounts are a good choice. This allows 10 million accounts, and accounts have a similar format to local numbers. Thus customers dial what appears to be a local number for calls within the system, a 10 (or 11 digit beginning with 1) number for all NANP external calls, and 011... for international calls. Since users dial 10 or 11 digits for all external calls, they do not need to be aware which area code your system is located in.
• For large systems elsewhere, 5 to 8 digit accounts work well.
• For small systems, 3 to 5 digit accounts work well.

Per-customer prefixes

Optionally, account prefixes can be reserved for customers. This is a global option for the entire system, and must be enabled by the installer. If enabled, every time a customer is created, a prefix is automatically generated by the system for them. This prefix will be unique to the customer, and all their accounts will begin with this prefix. When calling between SIP telephones in the same customer, the prefix is optional.

This is suitable for a system with a small to medium number of business customers who need ranges of accounts. It is not so suitable for residential users, as they require few accounts each, and reserving a prefix for them wastes accounts. For example, if using 8 digit account numbers without prefixes, up to one hundred million accounts can be created. If using 8 digit accounts with 5 digit prefixes, up to ten thousand customers each with up to one thousand accounts can be created.