Modems also dial the line, answer the call, and control transmission speed.
Modems also have automatic feature negotiation, which adjusts to the other modem's speed and hardware protocols. Analog modems are relatively slow compared to ISDN and DSL, but are fast enough for most users, require the fewest changes for the user, and are the least expensive of any of the remote access connectivity options. Verizon ESG - has a policy to disconnect after 30 minutes of undetected activity. The Penn-ISC modem pool is limited to 1 hour of connection time between 6 PM and 12 o clock, midnight, and 4 hours of connection time between 12 o clock midnight and 6 PM the following day. The Penn-Express modem pool is limited to a 15 minute session.