This Internet Fax Service Buyer's Guide is a work in process. Feel free to add your suggestions and comments as replies to this post.
Internet Fax Reception Features
Can you get inbound numbers in your area code/ in other area codes? If you wish to have your fax number in the same area code as your phone number, verify that the provider offers numbers in your area code.
Can you get inbound numbers in different countries? If you wish to create a virtual presence in another country, verify that the provider can offer numbers overseas. Or select a provider in your required destination country.
Can you receive faxes in different formats (TIF, JPG, PDF)? With most internet fax service providers, inbound faxes are received as TIF file attachments. If you have special file format requirements - for example if you require compatibility with existing document management systems - verify that the provider can offer different formats. Common alternative formats are Acrobat PDF, JPEG/JPG and GIF.
Can you set your fax identifier (CSID) for inbound faxes? Your inbound CSID is an identifier which appears on the sending party's little fax screen and on confirmation reports. It is how you are identified to the sender.
Can you easily change your inbound email address? Does the internet fax service provider offer an online interface to make changes to your account? You should be able to change the email address at which you receive your faxes at a moment's notice.
Can you resend an inbound fax to your email address? Your email may sometimes fail to receive an inbound fax - for example, due to a full mailbox or a communications failure - or you may inadvertently have deleted a received fax. The provider should offer a method for you to resend received faxes to your mailbox.
Can you receive faxes to more than one email address? You may wish to receive faxes to a backup address, or your business may have fax archiving requirements. Verify that the provider can forward your faxes to as many email addresses as you require.
Can you receive faxes by encrypted/signed email? Email is an open communications protocol, readable by anyone with access to its path. Public-key encryption can secure your faxes from prying eyes and verify that the fax you have received originates with the fax service provider. A security-conscious provider will enable you to upload your public key into the system and have all faxes emailed to you in encrypted format.
Can you view inbound activity online? The provider should offer online screens through which you can follow your fax reception activity.
Is there a test period/money-back guarantee? This should give you at least 30 days to try the service at no cost. If a setup charge applies - it should be refunded to you if you decide not to continue the service.
Internet Fax Transmission Features
Can you send faxes in your required formats (DOC, JPG, TXT, etc.)? Most internet fax service providers support a variety of document formats to be sent as attachments. What matters most is not who supports the most file formats, but who supports the file formats that YOU require. Also, how willing are they to support additional file formats you may require?
Can you set your fax identifier (CSID) for outbound faxes? The CSID is part of the fax header (date, page x of y, etc.). It indicates who the sender is, and is even a legal requirement in some locations. Can you set this identifier to show your details, or does the provider insist on advertising himself by setting the CSID to his name?
Can you send faxes from more than one email address? Can you send faxes from more than one user in the office? Can you send faxes from your home address or Yahoo! mail? A provider should enable you to set numerous email addresses from which faxes may be sent. Some provider may require an additional charge for additional sender addresses
Can the internet fax service provider accept encrypted emails for outbound faxes?
Does the internet fax service provider supply any privacy features?
Can you receive confirmations of fax results by email?
Can you view outbound activity online?
Is it easy to resubmit failed faxes?
Can you run fax broadcasts through the service?
If yes, can you automatically merge fields into the document?
Can you manage your own lists online?
Can more than one outbound user be defined under an account?
Costs - Fax Reception
Does the internet fax service provider charge a setup fee? A setup fee is a one-time charge associated with allocating your fax number and opening your account.
Does the internet fax service provider charge a monthly subscription fee? A monthly subsription fee is applied regardless of whether or not you have received any faxes. This fee may cover unlimited reception of faxes or it may be limited.
Is there a limit on how many faxes you can receive? An internet fax service provider may limit the number of faxes you can receive and require an additional per-page fee once this limit is exceeded.
If yes, how much is charged for each additional fax/page received? Make sure to find out whether the fee is per page or per fax.
If free - what are the limitations? Some internet fax service providers will attach terms to free usage of their service. For example, they might restrict the service to personal use. Or they might limit the number of faxes you may receive in a given time period. Other restrictions may apply.
Costs - Fax Transmission
Does the internet fax service provider charge a setup fee? A setup fee is a one-time charge associated with opening your account.
Does the internet fax service provider charge a monthly subscription fee? A monthly subsription fee is applied regardless of whether or not you have sent any faxes. This fee may include a number of free monthly pages/faxes.
How much does the internet fax service provider charge per fax/page/minute?Normally providers will charge by page. Some providers add a condition that faxed pages longer than one minute in duration will be charged extra. Pay attention to the additional increment here, too. For example, for a 66-second one-fax some providers may charge the equivalent of 2 pages, while some providers will charge for 1.1 pages, while others may only charge for the one page.
Note: Some internet fax service providers quote 30-second increments. Since faxes are almost never shorter than 30 seconds, you will end up paying up to twice the quoted price. Always make sure you're comparing apples with apples!
If prepaid - does the prepaid payment expire if unused for a certain time? Internet fax service providers who require pre-payment for fax transmission will sell a bulk of pages/minutes to be consumed incrementally. Some subscribers limit the length of time during which you may consume this pre-payment.
Internet fax service provider Features
Does the provider offer support? If yes, how (by phone, email)?
Is support free, paid?
How long does it take for a sales rep to call you back?
How long does it take to get a support email answered?
Does the provider have an emergency "out of service" notification phone number?
How long has the provider been in business?
Does the provider operate his own equipment our outsource operations?
How many faxes does the provider send per month?
Can more than one user be defined under an account?
Does the service offer a programmer API?
Is the provider responsive to feature requests?
Can you receive summary reports by email?