SME and startup companies are always looking for ways to increase the productivity of their employees and increase their revenue. There are many open-source software alternatives available that can be used for free and are more than enough to start your business and keep the ball rolling.
To manage customers and leads coming to your website and to track the activity of your sales team, you will also need a CRM solution. Salesforce and Oracle CRM are the commercial CRM tools that usually are preferred by large enterprises. If you just wish to get things done freely, then try SugarCRM, OpenCRX and Fat Free CRM.
As a startup, you may also need Cloud Telephony services so that customers can reach out to you. You will not want to put mobile numbers on the website, right? Your customers should feel that they are calling a landline number which is in the reception of your office. To get that feel, you will need a cloud telephony number but that is not something you can get at a low price. There are commercial alternatives like Exotel, Knowlarity but some open-source alternatives can be AsteriskNOW and Elastix