Unit 1: Shall I put you through? Telephoning basics, identifying yourself, getting through. 

Unit 2: Could you spell that for me? Exchanging and checking information, spelling over the phone. 

Unit 3: Let me get back to you on that: Voicemail greetings, leaving and taking messages, prepositions. 

Unit 4: When would suit you? Making and confirming arrangements, times and dates, mobile phone calls. 

Unit 5: I'm very sorry about that: Making and dealing with complaints, technical support, telephone customer care. 

Unit 6: How does that sound? Making and reacting to proposals, reaching agreements.