Choosing a CTI( Computer Telephony Integration) card might not be easy for them who are going to deploy them for the first time or who want to develop their first IVR Application. I am trying to give a short introduction of CTI cards and some thumbs rule to pick your first CTI card.
Number of Port Or Number of Channels:
CTI cards come in number of channels or ports! It means number of telephone lines you can connect to the CTI card and number of calls your IVRS will be able to handle simultaneously. So for development purpose, you might be interested in a single port or single channel! But such is life, you will not find any single port CTI cards! The minimum number of ports/channels in a CTI card is normally 4! But then it makes sense! In a real life and real world situations, single port IVRS will be of no use! Even in development, if you could get a single port card to test, how could you make an application which would handle two or more channels/ports? So, you have to buy a 4PORT CTI cards! Be prepared, if you ask any vendor for a CTI Card, first thing they would ask is how many ports or channels! Smartly reply that you are looking for a 4Port card!
Analog or Digital
CTI card should be analog or digital ? well, this is little confusing, it actually means CTI card will connect to Telephone Exchange ( EPABX) using digital technology or analog technology ? By analog technology, we mean a telephone line ( which you connect to a telephone instrument) connectivity to the CTI card. How is it analog ? well, it uses TIP and RING connection, you know there is a call on the phone when there is a RING, and you UNHOOK, or lift the telephone headset to connect the call! You know the caller has disconnected when you hear engage tone! (I hope you know what is and engage tone). So, the analog CTI card detects the RING, unhooks the phone, and it detects ENGAGE TONE and it ONHOOK the phone to disconnect, puts the headset on the cradle! So all these activities are analog and takes time! And also there is limitation of number of channels! But in a digital connectivity, all those like RING, Disconnect Tone(engage Tone), everything comes in messages! And they use digital links. And all these jargons like E1/T1, ISDN PRI, R2MF, SS7 comes in! These are digital protocols to connect the CTI t the telephone exchanges! And the minimum number of channels in a DIGITAL CTI card is 30 voice ports! It uses a 2MBPS link. The number of voice channels will go up to 31 if you use a SS7 protocol on the same 2MBPS link (commonly known as E1 or PCM). So, the thumb rule is settle for analog card if you number of channels requirement is less that 20. Else go for a digital card.
Development SDK and Tools
Most important part for developers is, what SDK(Software Development Kit) the CTI vendor provides and on what platforms! Normally one should opt for a CTI cards who has SDKs for MS Windows, UNIX/LINUX and also Sun Solaris! Though configuration for Analog cards are normally pretty easier than their digital counterparts! So, if you are a new in the field, technical support is a must from the vendor! And if you have to go for a digital card, ahem, you choose only a CTI Card vendor who has a very good technical support! Else you are asking for a trouble!
Well, you will have to negotiate with the vendor!