One Lead/Sr Tech with Call Center experience to be responsible for hardware, software(backups/upgrades), ARS/AAR, Trunking, VDN/Vectors, trouble shooting and general organization as well as setting SLA standards and creating a tracking method of work load. And one grunt to do most of the simple MAC extension programming and physical moves.
Also depends on how often people move around. If they stay in one spot for the most part, than one would suffice. But, it doesn't take much for one person to get overloaded or burned out when he/she is running between a call center and executive offices.
Lead takes the Call Center keeping the bread and butter of the operations happy while the grunt gets some executive face time keeping the front offices happy.